RESUMEN
The present study was designed to analyze protein expression in lungs from pulmonary hypertensive rats in order to identify novel signaling pathways. This was achieved by proteomic studies in which proteins from lung homogenates from hypoxic were compared to normoxic rats. The expression of these proteins was then investigated in lungs from hypoxic rats treated with either an activator of soluble guanylyl cyclase, BAY 412272, or an inhibitor of phosphodiesterase type 5, sildenafil. The proteomic study revealed an up-regulation of guanine nucleotide-binding protein ß, GST-ω-1, cathepsin D, chloride intracellular channel subunit 5, annexin A4, F-actin capping protein CapZ (CapZα), and the translation factor elongation factor 1 δ in lungs from chronic hypoxic rats with pulmonary hypertension. Immunohistochemistry revealed that CapZα, cathepsin D, and annexin A4 were expressed in the pulmonary vascular wall and immunoblotting showed these proteins correlated to alterations in muscularization. Both drugs inhibited hypoxia-induced increase in right ventricular systolic pressure and pulmonary arterial muscularization, and prevented most of the protein regulations observed after hypoxia. These findings suggest that pulmonary pressure is an important factor for initiating signaling pathways leading to protein expression and muscularization in the pulmonary vasculature.
Asunto(s)
Regulación de la Expresión Génica/efectos de los fármacos , Hipertensión Pulmonar/genética , Pulmón/efectos de los fármacos , Pulmón/fisiopatología , Proteoma/análisis , Proteoma/genética , Secuencia de Aminoácidos , Animales , Guanilato Ciclasa/metabolismo , Hemodinámica , Hipertensión Pulmonar/metabolismo , Hipertensión Pulmonar/fisiopatología , Hipoxia/genética , Hipoxia/metabolismo , Pulmón/irrigación sanguínea , Pulmón/metabolismo , Masculino , Datos de Secuencia Molecular , Inhibidores de Fosfodiesterasa 5/farmacología , Piperazinas/farmacología , Proteoma/metabolismo , Proteómica , Purinas/farmacología , Pirazoles/farmacología , Piridinas/farmacología , Ratas , Ratas Wistar , Transducción de Señal , Citrato de Sildenafil , Sulfonas/farmacologíaRESUMEN
A proteomic approach was applied to explore the signalling pathways elicited by lowering O(2) in endothelial cells. Endothelial cells isolated from native umbilical cords were subjected to 21, 5, or 1% O(2) for 24 h. 2-D PAGE was performed and candidate proteins were identified using LC-MS/MS. Lowering of O(2) from 21 to 5% induced upregulation of cofilin-1, cyclophilin A, tubulin and tubulin fragments, a fragment of glucose-regulated protein 78 (Grp78) and calmodulin. The upregulation of Grp78 suggested that ER stress proteins were altered and indeed Grp94 and caspase 12 expression were increased in cells exposed to 5% O(2). The presence of ER stress is also supported by findings of blunted caffeine-evoked ER calcium release in cells exposed to 5 and 1% O(2). Exposure to 1% O(2) caused increases in cofilin-1, cyclophilin A, and caspase 12 as well as a decrease of beta-actin, but it did not alter the expression of calmodulin, tubulin, Grp78, and Grp94. Incubation with CoCl(2), a stabilizer of the hypoxia-inducible factor, increased the expression of several of the proteins. The present investigations reveal that lowering O(2), probably in part through hypoxia-inducible factor, alter the expression of a series of proteins mainly involved in cytoskeletal changes (e.g. cofilin-1, tubulin, and beta-actin) and in ER stress/apoptosis (e.g. Grp78/94, caspase 12, and cyclophilin A).
Asunto(s)
Proteínas del Citoesqueleto/metabolismo , Retículo Endoplásmico/metabolismo , Células Endoteliales/metabolismo , Proteínas de Choque Térmico/metabolismo , Hipoxia , Oxígeno/metabolismo , Secuencia de Aminoácidos , Calcio/metabolismo , Calmodulina/metabolismo , Caspasa 12/metabolismo , Células Cultivadas , Ciclofilina A/metabolismo , Chaperón BiP del Retículo Endoplásmico , Células Endoteliales/citología , Femenino , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia , Glicoproteínas de Membrana/metabolismo , Datos de Secuencia Molecular , Embarazo , Proteómica/métodos , Transducción de Señal/fisiología , Cordón Umbilical/citologíaRESUMEN
Although the historical bases for graduate training in the United Kingdom (UK) and Scandinavia both stem from the original concept developed by von Humboldt, and both award a 'PhD degree', their paths have diverged. There are thus significant differences in the manner in which graduate training is organised. To analyse these differences, two UK graduate programmes (School of Medicine, Cardiff University; Institute of Integrative Biology, University of Liverpool) and two Scandinavian graduate schools (Faculty of Medicine and Dentistry, University of Bergen; Karolinska Institutet, Stockholm) completed a Self-evaluation questionnaire developed by Organisation of PhD Education in Biomedicine and Health Sciences in the European System (ORPHEUS)). Analysis of the completed questionnaires shows differences concerning requirements for admission, the training content of PhD programmes, the format of the PhD thesis, how the thesis is assessed and the financial model. All programmes recognise that PhD training should prepare for employment both inside and outside of academia, with emphasis on transferable skills training. However, the analysis reveals some fundamental differences in the direction of graduate programmes in the UK and Scandinavia. In the UK, graduate programmes are directed primarily towards teaching PhD students to do research, with considerable focus on practical techniques. In Scandinavia, the focus is on managing projects and publishing papers. To some extent, the differences lead to a lack of full recognition of each other's theses as a basis for doing a postdoc. This paper describes the basis for these differences and compares the two approaches and points to areas in which there is, or might be, convergence.
Asunto(s)
Educación de Postgrado/estadística & datos numéricos , Educación de Postgrado en Medicina , Educación de Posgrado en Odontología/estadística & datos numéricos , Educación de Postgrado en Medicina/estadística & datos numéricos , Noruega , Suecia , Reino Unido , UniversidadesRESUMEN
The cardiovascular effects of tyramine, and its interactions with propranolol, atenolol, phentolamine, prazosin, yohimbine and atropine, have been investigated in anesthetized rats in vivo and in vitro. Tyramine (i.v.) increased both the mean arterial blood pressure and heart rate. Phentolamine, prazosin or a combination of prazosin and yohimbine caused an inhibition of the hypertensive effect of tyramine, but propranolol, atenolol and/or atropine had no effect. Propranolol added to rats receiving atropine depressed the chronotropic effect of tyramine. However, in non-atropinized animals, the positive chronotropic effect of tyramine was paradoxically enhanced by propranolol, and further enhanced by atropine. A similar result was found with atenolol pre-treated animals. Phentolamine did not alter the effects of propranolol and atropine on heart rate. Prazosin depressed the positive chronotropic effects of tyramine, and this effect was re-stored by pre-treatment of the animals with both prazosin and yohimbine. In the isolated atria, propranolol--in contrast to the in vivo results--inhibited the chronotropic effect of tyramine. Atropine potentiated the positive inotropic effect of isoproterenol and tyramine. Tyramine produced a concentration-dependent contraction of isolated thoracic aortic rings, and this was potentiated by N(G)-nitro-l-arginine, or by removal of the endothelium, but inhibited by phentolamine. The in vivo and in vitro effects of tyramine were not seen in rats which had been treated with reserpine. We conclude that the positive inotropic and chronotropic effects of tyramine in the rat are due to indirect release of transmitter. The results suggest that the paradoxical enhancement by propranolol and atenolol of the chronotropic effect in vivo could be due to tyramine causing increased vagal activity, such that an inhibitory effect of propranolol can only be revealed in animals treated with atropine.
Asunto(s)
Antagonistas Adrenérgicos alfa/farmacología , Antagonistas Adrenérgicos beta/farmacología , Parasimpatolíticos/farmacología , Simpatomiméticos/farmacología , Tiramina/farmacología , Animales , Aorta Torácica/efectos de los fármacos , Aorta Torácica/metabolismo , Presión Sanguínea/efectos de los fármacos , Catecolaminas/metabolismo , Relación Dosis-Respuesta a Droga , Interacciones Farmacológicas , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Técnicas In Vitro , Ratas , Ratas Wistar , Simpatomiméticos/administración & dosificación , Tiramina/administración & dosificaciónRESUMEN
Antipsychotic drugs often cause orthostatic hypotension, probably through antagonist action on resistance vessel alpha(1A)-adrenoceptors. Here we have tested this possibility directly using cells transfected with a relevant human alpha(1A)-adrenoceptor splice variant. To determine a splice variant which was relevant, we used quantitative real-time polymerase chain reaction (qPCR) to determine the prevalence in human subcutaneous small arteries of three of the five splice variants ADRA1A_v1-5, which encode functional protein: alpha(1A1)-, alpha(1A3)-, alpha(1A4)-adrenoceptors. Our statistical analysis showed higher transcription levels of alpha(1A1)- than of alpha(1A3)- and alpha(1A4)-adrenoceptors (1.6 and 5.8 times, respectively). We therefore chose to study the alpha(1A1)-adrenoceptor, and the cDNA encoding it was transfected into the Flp-In-293 (modified from HEK-293) cell line to produce a cell line stably expressing a functional form of this splice variant. The expression of recombinant alpha(1A1)-adrenoceptor subtype was confirmed by Western immunoblot analysis, and its functionality demonstrated using a Fura-2 assay by a rise in intracellular calcium concentration ([Ca(2+)](i)) when challenged with phenylephrine (EC(50)=1.61x10(-8) M). From Schild analysis, prazosin, sertindole, risperidone, and haloperidol caused a concentration-dependent, rightward shift of the cumulative concentration-response curves for phenylephrine in cells expressing human recombinant alpha(1A1)-adrenoceptors to yield pK(B) values of 8.40, 8.05, 8.26 and 7.38, respectively. In [7-methoxy-(3)H]-prazosin binding experiments, high expression was seen (B(max)=48.5+/-16.7 pmol/mg protein, +/-S.E.M.) along with high affinity binding to a single site (K(d)=0.210+/-0.034 nM). The pharmacological profiles of recombinant human alpha(1A1)-adrenoceptors in competition binding studies confirmed much higher antagonist affinity of sertindole and risperidone than haloperidol for these receptors. In summary, it can be concluded that there is an approximately 10-fold higher adrenoceptor affinity of risperidone and sertindole for human alpha(1A1)-adrenoceptors compared to haloperidol. These findings are consistent with the observation that risperidone and sertindole have a higher incidence of orthostatic hypotension than haloperidol.
Asunto(s)
Antagonistas de Receptores Adrenérgicos alfa 1 , Antipsicóticos/farmacología , Antipsicóticos/efectos adversos , Arterias/metabolismo , Unión Competitiva , Calcio/metabolismo , Línea Celular , Haloperidol/efectos adversos , Haloperidol/farmacología , Humanos , Imidazoles/efectos adversos , Imidazoles/farmacología , Indoles/efectos adversos , Indoles/farmacología , Fenilefrina/farmacología , Prazosina/farmacología , Isoformas de Proteínas/antagonistas & inhibidores , Isoformas de Proteínas/biosíntesis , Isoformas de Proteínas/genética , Ensayo de Unión Radioligante , Receptores Adrenérgicos alfa 1/biosíntesis , Receptores Adrenérgicos alfa 1/genética , Proteínas Recombinantes/antagonistas & inhibidores , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , Risperidona/efectos adversos , Risperidona/farmacología , Piel/irrigación sanguínea , Tritio , Resistencia VascularRESUMEN
Nitric oxide has been shown to reduce the development of chronic hypoxic pulmonary hypertension. L-arginine is the substrate for endogenous nitric oxide synthesis. The aim of this study was to investigate whether oral L-arginine prevents the development of pulmonary vascular and right ventricular hypertrophy in adult chronic hypoxic rats. Male rats were maintained in either normoxic or hypobaric hypoxic (10% O(2)) chambers for two weeks as controls or treated with L-arginine (2 g kg(-1) day(-1) in the drinking water). Both in vehicle and L-arginine-treated rats, chronic hypoxia caused right ventricular hypertrophy, increased media to lumen ratio and increased lung weight. Contraction to the thromboxane analogue, U46619, was increased in intrapulmonary arteries, while systemic blood pressure was unaltered. Relaxations induced by the nitric oxide donor, S-nitroso-N-acetylpenicillamine (SNAP), were increased in arteries from L-arginine-treated normoxic and hypoxic animals. In conclusion, long-term oral L-arginine administration fails to prevent development of right ventricular hypertrophy and vascular media hypertrophy in adult chronic hypoxic rats.
Asunto(s)
Arginina/farmacología , Hipertrofia Ventricular Derecha/prevención & control , Hipoxia/fisiopatología , Arteria Pulmonar/efectos de los fármacos , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacología , Acetilcolina/farmacología , Administración Oral , Animales , Arginina/administración & dosificación , Presión Sanguínea/fisiología , Enfermedad Crónica , Hipertrofia Ventricular Derecha/fisiopatología , Pulmón/irrigación sanguínea , Pulmón/efectos de los fármacos , Pulmón/patología , Masculino , Óxido Nítrico/biosíntesis , Tamaño de los Órganos/efectos de los fármacos , Oxígeno/farmacología , Penicilamina/análogos & derivados , Penicilamina/farmacología , Arteria Pulmonar/patología , Arteria Pulmonar/fisiopatología , Ratas , Ratas Wistar , Vasoconstricción/efectos de los fármacos , Vasoconstrictores/farmacología , Vasodilatación/efectos de los fármacosRESUMEN
Essential hypertension is treated primarily with a view to reducing blood pressure, and not with regard to normalizing the main pathological changes: the peripheral resistance and the cardiovascular structure. The aim of this review is to discuss whether normalization of the latter parameters, in particular resistance vessel structure, may also be a target for therapy. The review presents first the evidence for altered structure of the resistance vasculature, an increase in the media:lumen ratio of the vessels due to inward eutrophic remodelling. Secondly the degree to which it may be possible to rectify the abnormal structure is discussed, where it is shown that there is strong evidence that this requires a therapy which causes vasodilatation in the patient concerned. Thirdly evidence is presented that altered small artery structure appears to have prognostic consequences. Fourthly, the cellular mechanisms which may be involved are discussed, where there is evidence that vasoconstriction in itself can cause inward remodelling, and that this can be prevented by vasodilators. Finally, the consequences of these findings are considered as regards clues for strategies that may be able to improve the outcome of antihypertensive therapy. The review concludes that there is reasonably strong evidence that a treatment which reduces peripheral resistance in the individual patient will, apart from reducing blood pressure, also improve the abnormal structure.
Asunto(s)
Arterias/patología , Hipertensión/patología , Microcirculación , Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Animales , Antihipertensivos/uso terapéutico , Humanos , Hipertensión/tratamiento farmacológico , Resistencia Vascular/efectos de los fármacos , Vasodilatadores/uso terapéuticoRESUMEN
AIM: Established essential hypertension is associated with increased arterial stiffness and peripheral resistance, but the extent of vascular changes in persons genetically predisposed for essential hypertension is uncertain. METHODS: Participants from the Danish Hypertension Prevention Project (DHyPP) (both parents hypertensive) (nâ=â95, 41â±â1 years, 53% men) were compared with available spouses (nâ=â45, 41â±â1 years) using measurements of ambulatory blood pressure (BP), left ventricular mass index (LVMI), pulse wave velocity, central BP and augmentation index (AIx) in addition to forearm resting and minimal resistance [forearm resting vascular resistance (Rrest) and forearm minimal vascular resistance (Rmin)]. RESULTS: DHyPP patients with participating spouses had higher 24-h mean BP (94â±â1 vs. 88â±â1âmmHg, Pâ<â0.01), LVMI (94â±â3 vs. 80â±â2âg/m, Pâ<â0.01), central SBP (121â±â2 vs. 111â±â2âmmHg, Pâ<â0.01) and AIx (16.0â±â1.2 vs. 10.5â±â1.7%, Pâ<â0.01), but similar carotid-femoral pulse wave velocity (7.5â±â0.2 vs. 7.1â±â0.2âm/s), Rrest (53â±â3 vs. 51â±â3âmmHg/ml/min/100âml) and log Rmin (0.58â±â0.02 vs. 0.55â±â0.02âmmHg/ml/min/100âml) when compared with spouses. Using multiple linear regression analysis (adjusting for sex, age, BMI, creatinine clearance and 24-h BP, heart rate and sodium excretion) AIx and LVMI remained elevated in DHyPP patients [4.2% (0.7; 7.7), Pâ=â0.02 and 6.3âg/m (0.7; 11.9), Pâ=â0.03]. For the entire DHyPP cohort AIx, Rrest and Rmin were higher in women than men (Pâ<â0.01), and the same was true for AIx and Rmin among spouses (Pâ<â0.05). Furthermore, AIx was linearly associated with Rrest and Rmin. CONCLUSION: Young to middle-aged individuals genetically predisposed for essential hypertension display increased AIx and LVMI, although vascular stiffness and peripheral resistance are still normal.
Asunto(s)
Hipertensión Esencial/genética , Predisposición Genética a la Enfermedad , Ventrículos Cardíacos/patología , Resistencia Vascular/genética , Rigidez Vascular/genética , Adulto , Presión Sanguínea , Monitoreo Ambulatorio de la Presión Arterial , Ecocardiografía , Femenino , Antebrazo/irrigación sanguínea , Ventrículos Cardíacos/diagnóstico por imagen , Humanos , Masculino , Tamaño de los Órganos , Padres , Análisis de la Onda del Pulso , Factores SexualesRESUMEN
OBJECTIVE: Correction of the abnormal structure of resistance arteries in essential hypertension may be an important treatment goal in addition to blood pressure (BP) reduction. We investigated how this may be achieved in a prospective clinical study. METHODS: Plethysmography was used to measure forearm resting vascular resistance (Rrest) and minimum vascular resistance (Rmin) as a measure of vascular structure. Two different groups of patients with essential hypertension were examined at baseline and after 6 months of antihypertensive treatment. In group A, 21 patients with never-treated essential hypertension were treated by their general practitioners using a variety of drugs to allow an assessment of the drug-independent effects. In group B, 28 beta-blocker-treated patients were shifted to angiotensin II receptor blocker treatment (eprosartan) to allow vasodilatation with no change in BP. RESULTS: In group A, mean ambulatory blood pressure (ABP) fell from 119 +/- 2 (SE) to 103 +/- 2 mmHg (P < 0.01), whereas mean ABP was unchanged in group B (100 +/- 1 to 99 +/- 1 mmHg, P = NS). Both groups showed similar reductions in Rrest (-33.4 and -28.5%, respectively) and in Rmin (-15.4 and -15.6%, respectively). There was a strong correlation between changes in Rrest and Rmin within both groups (r = 0.57, P < 0.01 and r = 0.68, P < 0.0001, respectively), whereas the change in BP in group A was not correlated to the change in Rmin (r = -0.03). CONCLUSION: The correction of forearm resistance artery structure during antihypertensive treatment depends on the vasodilatation achieved rather than BP reduction.
Asunto(s)
Antihipertensivos/farmacología , Arterias/efectos de los fármacos , Presión Sanguínea/efectos de los fármacos , Resistencia Vascular/efectos de los fármacos , Vasodilatación/efectos de los fármacos , Acrilatos/farmacología , Adulto , Estudios de Casos y Controles , Ecocardiografía , Femenino , Humanos , Imidazoles/farmacología , Masculino , Persona de Mediana Edad , Tiofenos/farmacología , Función Ventricular Izquierda/efectos de los fármacosRESUMEN
OBJECTIVE: Structural abnormality of resistance arteries is a characteristic pathophysiological phenomenon in essential hypertension and can be assessed in vitro as an increase in the media: lumen ratio (M: L) of isolated small arteries. We have investigated whether M: L is a risk predictor in uncomplicated essential hypertensive patients. Recently, high M: L was demonstrated as a prognostic marker in patients at high cardiovascular risk, including normotensive type 2 diabetic patients. Since diabetes is associated with pressure-independent changes in M: L, the relevance of this finding to essential hypertension has been uncertain. METHODS: We conducted a follow-up survey of 159 essential hypertensive patients, who had previously been submitted to a M: L evaluation while participating in a clinical trial. They composed a homogeneous moderate-risk group, with no concomitant diseases, and represented 1661 years of follow-up. RESULTS: Thirty patients suffered a documented predefined cardiovascular event during follow-up. Increased relative risk (RR) was associated with M: L >or= 0.083 (mean level of the hypertensive cohort), RR = 2.34 [95% confidence interval (CI) 1.11-4.95], and with M: L >or= 0.098 (mean level of a normotensive control group + 2SD), RR = 2.49 (95% CI 1.21-5.11). Both results remained significant (RR = 2.19, 95% CI 1.04-4.64, and RR = 2.20, 95% CI 1.06-4.56, respectively) when adjusted for Heart Score level (10-year mortality risk-estimate, integrating age, gender, systolic blood pressure, cholesterol and smoking). CONCLUSION: Abnormal resistance artery structure independently predicts cardiovascular events in essential hypertensive patients at moderate risk.
Asunto(s)
Arterias/patología , Hipertensión/patología , Túnica Media/patología , Adulto , Nalgas/patología , Enfermedades Cardiovasculares/diagnóstico , Femenino , Humanos , Hipertensión/complicaciones , Masculino , Persona de Mediana Edad , PronósticoRESUMEN
BACKGROUND/AIMS: We investigated whether the tissue transglutaminase inhibitor cystamine is able to inhibit remodelling of small arteries in vivo, a possibility suggested by recent in vitro experiments. METHODS: Using osmotic minipumps, phenylephrine, cystamine and/or amlodipine were infused for 1-2 weeks into 9-week-old Wistar rats. Small arteries were then removed for pressure myograph investigation. RESULTS: Phenylephrine infusion caused inward remodelling of the small arteries compared to vehicle infusion. The remodelling was abolished by concomitant infusion with cystamine; blood pressure was unaffected. Second, we investigated whether cystamine was able to inhibit outward remodelling. Rats were first infused with phenylephrine for 1 week, and some were infused for a further week with amlodipine with or without cystamine. Amlodipine caused 24% outward remodelling compared to vessels from rats at completion of the phenylephrine infusion. The outward remodelling was attenuated 86% by concomitant cystamine infusion. A series of in vitro experiments supported the inhibitory action of cystamine on tissue transglutaminase. CONCLUSION: The ability of cystamine to inhibit inward remodelling independent of blood pressure is consistent with a role of tissue transgluaminase in this process. It remains to be determined if the ability of cystamine to inhibit outward remodelling also involves inhibition of tissue transglutaminase.
Asunto(s)
Amlodipino/farmacología , Antihipertensivos/farmacología , Cistamina/farmacología , Inhibidores Enzimáticos/farmacología , Proteínas de Unión al GTP/antagonistas & inhibidores , Hipertensión/tratamiento farmacológico , Arterias Mesentéricas/efectos de los fármacos , Transglutaminasas/antagonistas & inhibidores , Amlodipino/administración & dosificación , Amlodipino/uso terapéutico , Animales , Antihipertensivos/administración & dosificación , Antihipertensivos/uso terapéutico , Presión Sanguínea/efectos de los fármacos , Colágeno/metabolismo , Cistamina/administración & dosificación , Cistamina/uso terapéutico , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/administración & dosificación , Inhibidores Enzimáticos/uso terapéutico , Proteínas de Unión al GTP/metabolismo , Geles , Frecuencia Cardíaca/efectos de los fármacos , Hipertensión/enzimología , Hipertensión/patología , Hipertensión/fisiopatología , Inmunohistoquímica , Bombas de Infusión , Masculino , Arterias Mesentéricas/enzimología , Arterias Mesentéricas/patología , Microscopía Confocal , Fenilefrina , Proteína Glutamina Gamma Glutamiltransferasa 2 , Ratas , Ratas Wistar , Transglutaminasas/metabolismo , Vasoconstricción/efectos de los fármacos , VasoconstrictoresRESUMEN
Remodeling of small arteries is essential in the long-term regulation of blood pressure and blood flow to specific organs or tissues. A large part of the change in vessel diameter may occur through non-growth-related reorganization of vessel wall components. The hypothesis was tested that tissue-type transglutaminase (tTG), a cross-linking enzyme, contributes to the inward remodeling of small arteries. The in vivo inward remodeling of rat mesenteric arteries, induced by low blood flow, was attenuated by inhibition of tTG. Rat skeletal muscle arteries expressed tTG, as identified by Western blot and immunostaining. In vitro, activation of these arteries with endothelin-1 resulted in inward remodeling, which was blocked by tTG inhibitors. Small arteries obtained from rats and pigs both showed inward remodeling after exposure to exogenous transglutaminase, which was inhibited by addition of a nitric oxide donor. Enhanced expression of tTG, induced by retinoic acid, increased inward remodeling of porcine coronary arteries kept in organ culture for 3 days. The activity of tTG was dependent on pressure. Inhibition of tTG reversed remodeling, causing a substantial increase in vessel diameter. In a collagen gel contraction assay, tTG determined the compaction of collagen by smooth muscle cells. Collectively, these data show that small artery remodeling associated with chronic vasoconstriction depends on tissue-type transglutaminase. This mechanism may reveal a novel therapeutic target for pathologies associated with inward remodeling of the resistance arteries.
Asunto(s)
Biotina/análogos & derivados , Proteínas de Unión al GTP/fisiología , Arterias Mesentéricas/fisiología , Transglutaminasas/fisiología , Vasoconstricción/fisiología , Sistema Vasomotor/fisiología , Aminas/farmacología , Animales , Arterias/efectos de los fármacos , Arterias/enzimología , Biotina/farmacología , Cadaverina/farmacología , Tamaño de la Célula/efectos de los fármacos , Colágeno , Vasos Coronarios/citología , Reactivos de Enlaces Cruzados/farmacología , Cistamina/farmacología , Endotelina-1/farmacología , Inducción Enzimática/efectos de los fármacos , Matriz Extracelular/ultraestructura , Proteínas de la Matriz Extracelular/química , Proteínas de la Matriz Extracelular/efectos de los fármacos , Femenino , Proteínas de Unión al GTP/biosíntesis , Proteínas de Unión al GTP/genética , Proteínas de Unión al GTP/farmacología , Geles , Cobayas , Hemorreología , Arterias Mesentéricas/enzimología , Músculo Esquelético/irrigación sanguínea , Miocitos del Músculo Liso/citología , Óxido Nítrico/fisiología , Donantes de Óxido Nítrico/farmacología , Nitroprusiato/farmacología , Norepinefrina/farmacología , Técnicas de Cultivo de Órganos , Papaverina/farmacología , Proteína Glutamina Gamma Glutamiltransferasa 2 , Ratas , Sus scrofa , Transglutaminasas/biosíntesis , Transglutaminasas/genética , Transglutaminasas/farmacología , Tretinoina/farmacología , Vasoconstricción/efectos de los fármacos , Vasoconstrictores/farmacología , Vasodilatadores/farmacologíaRESUMEN
The PhD degree was established in Berlin 200 years ago and has since spread across the whole world. While there is general agreement that the degree is awarded in recognition of successfully completed research training, there have been significant differences in the way doctoral training programs have developed in particular countries. There is, however, a clear global tendency to follow the programs currently used either in the United States or in Europe. To determine more clearly how US and European PhD programs are both similar and different, we have used a validated questionnaire to analyze biomedical PhD programs in four representative institutions at Vanderbilt University, University of Manitoba, Karolinska Institutet, and Graz Medical University. The analysis is based on 63 detailed questions concerning the research environment, outcomes, admission criteria, content of programs, mentoring (or supervising), the PhD thesis, assessment of the thesis, and PhD school structure. The results reveal that while there is considerable overlap in the aims and content of PhD programs, there are also considerable differences regarding the structure of PhD programs, mentoring and assessment of PhD theses. These differences are analyzed in detail in order to provide a foundation for discussion of their relative advantages and disadvantages, with a view to providing a platform for discussion of best practices. The results will be of importance in the continued development of global discussion about development of doctoral training.
RESUMEN
In human resistance arteries the role of intracellular calcium during receptor agonist and nitric oxide (NO)-mediated vasorelaxation is almost unknown. We examined changes in smooth muscle calcium concentration ([Ca2+]i) caused by acetylcholine and the NO donor S-nitroso-N-acetylpenicillamine (SNAP) in isolated human subcutaneous small arteries. In arteries constricted with 50 mM KCl, acetylcholine and SNAP induced relaxation without any change in [Ca2+]i, whereas in noradrenaline constricted vessels, both acetylcholine and to a lesser degree also SNAP-mediated relaxation were associated with a decrease in [Ca2+]i. Furthermore incubation with SNAP (1 microM) induced a rightward shift in the [Ca2+]i-force relationship. These results suggest that relaxation mediated by endothelium derived hyperpolarizing factors (EDHF) is associated with reduction in [Ca2+]i, whereas NO-mediated relaxation can take place without changes in [Ca2+]i. This finding seems to be, at least partly, due to NO-mediated desensitization of the contractile apparatus to calcium.
Asunto(s)
Acetilcolina/farmacología , Arterias/efectos de los fármacos , Calcio/metabolismo , Músculo Liso Vascular/efectos de los fármacos , Óxido Nítrico/fisiología , Vasodilatación/efectos de los fármacos , Arterias/fisiología , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Humanos , Técnicas In Vitro , Líquido Intracelular/efectos de los fármacos , Líquido Intracelular/metabolismo , Músculo Liso Vascular/citología , Músculo Liso Vascular/metabolismo , Donantes de Óxido Nítrico/farmacología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Nitroarginina/farmacología , Norepinefrina/farmacología , Penicilamina/análogos & derivados , Penicilamina/farmacología , Cloruro de Potasio/farmacología , Vasoconstricción/efectos de los fármacos , Vasodilatadores/farmacologíaRESUMEN
AIM: Young individuals genetically predisposed for essential hypertension have increased renal vascular resistance. We evaluated whether 1 year of angiotensin II receptor blockade decreases afferent arteriolar resistance (RA) and induces a sustained blood pressure (BP) reduction during a 10-year follow-up period in offspring of parents both diagnosed with essential hypertension. METHODS: Based on renal plasma flow (p-aminohippurate clearance) and glomerular filtration rate (Cr-EDTA clearance) RA was calculated according to the model originally established by Gomez. Following baseline measurements, the participants (nâ=â110, mean age 30 years) were randomly allocated to 12 months of treatment with either candesartan or placebo followed by repetition of measurements and withdrawal of medication. Four-hour ambulatory BP (ABP) was recorded at baseline, by end of active treatment and after 6 months, 1, 2, 3, 5, and 10 years. ABP was analyzed according to RA achieved at the end of active treatment. RESULTS: Candesartan reduced RA by 14% (Pâ<â0.01). Ten years posttreatment systolic ABP increased by 2.1âmmHg (Pâ=â0.04) and diastolic by 4.2âmmHg (Pâ<â0.01) compared with baseline, without any difference between treatment arms. A high posttreatment RA was associated with higher BP levels during follow-up, but long-term alterations in 24-h BP were similar in participants with low and high RA and not different between treatment arms. CONCLUSION: RA is associated with 24-h BP levels, but temporary lowering of BP and RA by candesartan does not prevent BP from increasing further. Prevention of hypertension appears not feasible by short-term inhibition of the rennin-angiotensin system in young adults.
Asunto(s)
Antihipertensivos/uso terapéutico , Bencimidazoles/uso terapéutico , Presión Sanguínea/efectos de los fármacos , Hipertensión/prevención & control , Tetrazoles/uso terapéutico , Resistencia Vascular/efectos de los fármacos , Adulto , Antagonistas de Receptores de Angiotensina/uso terapéutico , Arteriolas/fisiopatología , Compuestos de Bifenilo , Monitoreo Ambulatorio de la Presión Arterial , Dinamarca , Femenino , Estudios de Seguimiento , Humanos , Hipertensión/genética , Hipertensión/fisiopatología , Masculino , Sistema Renina-Angiotensina/efectos de los fármacos , Factores de TiempoRESUMEN
BACKGROUND AND PURPOSE: Vasodilatation may contribute to the neuroprotective and vascular anti-remodelling effect of the tissue transglutaminase 2 (TG2) inhibitor cystamine. Here, we hypothesized that inhibition of TG2 followed by blockade of smooth muscle calcium entry and/or inhibition of Rho kinase underlies cystamine vasodilatation. EXPERIMENTAL APPROACH: We used rat mesenteric small arteries and RT-PCR, immunoblotting, and measurements of isometric wall tension, intracellular Ca(2+) ([Ca(2+)]i ), K(+) currents (patch clamp), and phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and myosin regulatory light chain, in our experiments. KEY RESULTS: RT-PCR and immunoblotting revealed expression of TG2 in mesenteric small arteries. Cystamine concentration-dependently inhibited responses to phenylephrine, 5-HT and U46619 and for extracellular potassium. Selective inhibitors of TG2, LDN 27129 and T101, also inhibited phenylephrine contraction. An inhibitor of PLC suppressed cystamine relaxation. Cystamine relaxed and reduced [Ca(2+)]i in phenylephrine-contracted arteries. In potassium-contracted arteries, cystamine induced less relaxation without changing [Ca(2+)]i , and these relaxations were blocked by mitochondrial complex inhibitors. Blockers of Kv 7 channels, XE991 and linopirdine, inhibited cystamine relaxation and increases in voltage-dependent smooth muscle currents. Cystamine and the Rho kinase inhibitor Y27632 reduced basal MYPT1-Thr(855) phosphorylation, but only Y27632 reduced phenylephrine-induced increases in MYPT1-Thr(855) and myosin regulatory light chain phosphorylation. CONCLUSIONS AND IMPLICATIONS: Cystamine induced vasodilatation by inhibition of receptor-coupled TG2, leading to opening of Kv channels and reduction of intracellular calcium, and by activation of a pathway sensitive to inhibitors of the mitochondrial complexes I and III. Both pathways may contribute to the antihypertensive and neuroprotective effect of cystamine.
Asunto(s)
Cistamina/farmacología , Arterias Mesentéricas/fisiología , Canales de Potasio con Entrada de Voltaje/fisiología , Transglutaminasas/metabolismo , Vasodilatación/fisiología , Animales , Antimicina A/farmacología , Calcio/metabolismo , Complejo I de Transporte de Electrón/antagonistas & inhibidores , Complejo III de Transporte de Electrones/antagonistas & inhibidores , Técnicas In Vitro , Masculino , Arterias Mesentéricas/metabolismo , Fenilefrina/farmacología , Proteína Glutamina Gamma Glutamiltransferasa 2 , Proteína Fosfatasa 1/fisiología , Ratas Wistar , Rotenona/farmacología , Transglutaminasas/genética , Vasoconstricción/efectos de los fármacos , Vasodilatación/efectos de los fármacosRESUMEN
BACKGROUND: The alpha1-adrenergic receptors (alpha1-ARs) play a key role in cardiovascular homeostasis. However, the functional role of alpha1-AR subtypes in vivo is still unclear. The aim of this study was to evaluate the cardiovascular influences of alpha1b-AR. METHODS AND RESULTS: In transgenic mice lacking alpha1-AR (KO) and their wild-type controls (WT), we evaluated blood pressure profile and cardiovascular remodeling induced by the chronic administration (18 days via osmotic pumps) of norepinephrine, angiotensin II, and subpressor doses of phenylephrine. Our results indicate that norepinephrine induced an increase in blood pressure levels only in WT mice. In contrast, the hypertensive state induced by angiotensin II was comparable between WT and KO mice. Phenylephrine did not modify blood pressure levels in either WT or KO mice. The cardiac hypertrophy and eutrophic vascular remodeling evoked by norepinephrine was observed only in WT mice, and this effect was independent of the hypertensive state because it was similar to that observed during subpressor phenylephrine infusion. Finally, the cardiac hypertrophy induced by thoracic aortic constriction was comparable between WT and KO mice. CONCLUSIONS: Our data demonstrate that the lack of alpha1b-AR protects from the chronic increase of arterial blood pressure induced by norepinephrine and concomitantly prevents cardiovascular remodeling evoked by adrenergic activation independently of blood pressure levels.
Asunto(s)
Cardiomegalia/fisiopatología , Sistema Cardiovascular/fisiopatología , Hipertensión/fisiopatología , Receptores Adrenérgicos alfa 1/deficiencia , Angiotensina II/farmacología , Animales , Aorta/fisiología , Arteriolas/efectos de los fármacos , Arteriolas/fisiopatología , Factor Natriurético Atrial/genética , Factor Natriurético Atrial/metabolismo , Presión Sanguínea/efectos de los fármacos , Presión Sanguínea/genética , Cardiomegalia/inducido químicamente , Cardiomegalia/patología , Sistema Cardiovascular/efectos de los fármacos , Sistema Cardiovascular/patología , Ecocardiografía , Frecuencia Cardíaca/efectos de los fármacos , Frecuencia Cardíaca/genética , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/metabolismo , Ventrículos Cardíacos/patología , Hipertensión/inducido químicamente , Hipertensión/patología , Masculino , Mesenterio/irrigación sanguínea , Ratones , Ratones Transgénicos , Norepinefrina/farmacología , Tamaño de los Órganos/efectos de los fármacos , Tamaño de los Órganos/genética , Fenilefrina/farmacología , ARN Mensajero/metabolismo , Receptores Adrenérgicos alfa 1/genética , Receptores Adrenérgicos alfa 1/metabolismo , Vasoconstrictores/farmacología , Remodelación Ventricular/efectos de los fármacos , Remodelación Ventricular/genéticaRESUMEN
Nitric oxide (NO) donors could constitute an alternative to inhaled NO as treatment in some patients with pulmonary hypertension. Therefore, the present study investigated the relaxation mechanisms of a novel NO donor, 3-(3-chloro-2-methylphenyl)-5-[[4-methylphenyl)sulphonyl]amino]-)hydroxide (GEA 3175) in segments of human pulmonary arteries and bronchioles, which were mounted in microvascular myographs. GEA 3175 induced concentration-dependent relaxations and was more potent in pulmonary arteries than in bronchioles. A blocker of soluble guanylyl cyclase, 1H-[1,2,4]oxadiazolo[4,3,-a]quinoxalin-1-one (ODQ), and iberiotoxin, a blocker of large-conductance calcium-activated K channels, both reduced relaxations induced by GEA 3175 in pulmonary arteries and bronchioles. Combining of ODQ and iberiotoxin did not produce additional inhibition. GEA 3175 relaxation is mediated through guanylyl cyclase-dependent mechanisms followed by activation of large-conductance calcium-activated K(+) channels. The dilatation of both pulmonary small arteries and airways by GEA 3175 seems advantageous, if it is considered administered as inhalation therapy for pulmonary hypertension.
Asunto(s)
Donantes de Óxido Nítrico/farmacología , Arteria Pulmonar/efectos de los fármacos , Triazoles/farmacología , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacología , Albuterol/farmacología , Bronquios/efectos de los fármacos , Bronquios/fisiología , Broncodilatadores/farmacología , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Técnicas In Vitro , Masculino , Contracción Muscular/efectos de los fármacos , Músculo Liso/efectos de los fármacos , Músculo Liso/fisiología , Óxido Nítrico/farmacología , Oxadiazoles/farmacología , Péptidos/farmacología , Arteria Pulmonar/fisiología , Quinoxalinas/farmacología , Vasoconstrictores/farmacología , Vasodilatación/efectos de los fármacosRESUMEN
The present study addressed whether combined treatment with a phosphodiesterase type 5 inhibitor, sildenafil, and a nitric oxide donor, molsidomine, prevents development of pulmonary hypertension in chronic hypoxic rats. Two weeks of hypoxia increased right ventricular systolic pressure, and right ventricular and lung weight. Treatment with either sildenafil (10 mg/kg/day) or molsidomine (15 mg/kg/day) in drinking water reduced right ventricular systolic pressure and weight, while lung weight was unchanged. Combining sildenafil and molsidomine did not have additional effects compared to molsidomine alone. The number of muscularized pulmonary arteries with diameters below 50 microm was increased in vehicle and sildenafil-treated, but not in molsidomine-treated hypoxic rats. Acetylcholine relaxation was blunted in arteries from vehicle and molsidomine-treated, but not in sildenafil-treated rats. In conclusion, both sildenafil and molsidomine blunts pulmonary hypertension and right ventricular hypertrophy in chronic hypoxic rats, but no synergistic effects were observed.
Asunto(s)
Hipertensión Pulmonar/prevención & control , Molsidomina/análogos & derivados , Molsidomina/farmacología , Piperazinas/farmacología , Vasodilatadores/farmacología , Acetilcolina/farmacología , Actinas/análisis , Animales , Factor Natriurético Atrial/farmacología , Peso Corporal/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Inhibidores Enzimáticos/farmacología , Guanilato Ciclasa/antagonistas & inhibidores , Ventrículos Cardíacos/efectos de los fármacos , Ventrículos Cardíacos/fisiopatología , Hipertensión Pulmonar/fisiopatología , Hipoxia/fisiopatología , Pulmón/química , Pulmón/efectos de los fármacos , Pulmón/patología , Masculino , Molsidomina/administración & dosificación , Músculo Liso/química , Oxadiazoles/farmacología , Piperazinas/administración & dosificación , Arteria Pulmonar/efectos de los fármacos , Arteria Pulmonar/fisiopatología , Purinas , Quinoxalinas/farmacología , Ratas , Ratas Wistar , Citrato de Sildenafil , Sulfonas , Sístole , Vasodilatación/efectos de los fármacos , Vasodilatadores/administración & dosificaciónRESUMEN
OBJECTIVE: Investigation of the effect of hypertension on endothelium-dependent relaxation and release of nitric oxide (NO) in normotensive and renal hypertensive rats. DESIGN AND METHODS: Sprague-Dawley rats were randomly allocated into two groups: uninephrectomized controls and one-kidney one-clip (Goldblatt hypertension) hypertensive rats, a non-renin dependent model of hypertension. After 10 weeks and in the presence of the cyclooxygenase inhibitor indomethacin, simultaneous measurements of the NO concentration, measured with a NO-specific microelectrode and endothelium-dependent relaxation were performed in isolated rat superior mesenteric arteries. RESULTS: Addition of the NO scavenger, oxyhaemoglobin, showed that basal NO concentration was unaltered in arterial segments from hypertensive rats. In norepinephrine-contracted arteries, acetylcholine increased the NO concentration and caused relaxations, and both parameters were significantly reduced in renal hypertensive arteries. Relaxations induced by the NO donor, S-nitroso-N-acetylpenicillamine were reduced. The superoxide scavenger, superoxide dismutase, and the NO synthase substrate, l-arginine, did not change the increase in NO concentration or acetylcholine relaxation in arteries from normotensive or renal hypertensive animals. In contrast, the NO synthase inhibitor, asymmetric dimethyl l-arginine, reduced the NO concentration and acetylcholine relaxation, while these responses were abolished in the presence of oxyhaemoglobin. CONCLUSIONS: This study provides direct evidence that reduced endothelium-dependent relaxations in the superior mesenteric artery from renal hypertensive rats is due, at least in part, to diminished NO release. The reduced NO release and relaxation persist in the presence of excess of substrate for NO synthase.