RESUMEN
Background: Studies have indicated an association between Alzheimer's disease (AD) and increased risk of developing cardiovascular complications. Lifestyle modifiable factors, such as exercise and diet, are known to prevent cardio-cerebral disease. Recent studies demonstrate that hearts from early onset triple-transgenic AD mice exhibit pathologies, but it is not clear whether cardiovascular function is altered in this model. Methods: In this study, we measured in vivo cardiovascular function in 7-month-old male 3xTg mice and age-matched wild-type (WT) mice using high-frequency high-resolution ultrasound imaging. Results: Our findings indicated that aortic root measurements and interventricular septal dimensions were similar in 3xTg and wild-type mice. Systolic function, expressed as ejection fraction and fractional shortening, were decreased in 3xTg mice. Late (A) ventricular filling velocities, the early/atrial (E/A) ratio, and mitral valve deceleration time, all indices of diastolic function, were increased in 3xTg mice compared to WT mice. Treadmill exercise training and resveratrol supplementation in the diet for 5 months improved ejection fraction, fractional shortening, and restored diastolic deceleration times. Pulse wave velocity was ~33% higher in 3xTg, and accompanied by a significant increase in elastin fiber fragmentation within the aortic wall, which was associated with decrease in elastin content and fiber length. Aortic wall and adventitia thickness were increased in 3xTg mice compared to the WT group. Exercise training and resveratrol supplementation, or both, improved overall aortic morphology with no change in pulse wave velocity. Conclusion: Taken together, the results indicate that the aberrations in cardiac function and aortic elastin morphology observed in the 3xTg mouse model of AD can be prevented with exercise training and treatment with resveratrol. The benefits of regular exercise training and resveratrol supplementation of heart and aortic structure in the 3xTg mouse support the value of healthy lifestyle factors on cardiovascular health.
Asunto(s)
Enfermedad de Alzheimer/tratamiento farmacológico , Válvula Aórtica/efectos de los fármacos , Enfermedades Cardiovasculares/tratamiento farmacológico , Modelos Animales de Enfermedad , Condicionamiento Físico Animal , Resveratrol/farmacología , Enfermedad de Alzheimer/metabolismo , Animales , Válvula Aórtica/metabolismo , Enfermedades Cardiovasculares/metabolismo , Suplementos Dietéticos , Masculino , Ratones , Ratones Transgénicos , Análisis de la Onda del Pulso , Resveratrol/administración & dosificaciónRESUMEN
X-linked myotubular myopathy (XLMTM) is an isogenic muscle disease characterized by progressive wasting of skeletal muscle, weakness, and premature death of affected male offspring. Recently, the XLMTM gene knock-in mouse, Mtm1 p.R69C, was found to have a similar phenotype as the Mtm1 gene mutation in humans (e.g., central nucleation of small myofibers, attenuated muscle strength, and motor unit potentials). Using this rodent model, we investigated whether syngeneic cell therapy could mitigate muscle weakness. Donor skeletal muscle-derived myoblasts were isolated from C57BL6 wild-type (WT) and Mtm1 p.R69C (KI) mice for transplantation into the gastrocnemius muscle of recipient KI mice. Initial experiments demonstrated that donor skeletal muscle-derived myoblasts from WT and KI mice remained in the gastrocnemius muscle of the recipient KI mouse for up to 4 weeks posttransplantation. KI mice receiving syngeneic skeletal muscle-derived myoblasts displayed an increase in skeletal muscle mass, augmented force generation, and increased nerve-evoked skeletal muscle action potential amplitude. Taken together, these results support our hypothesis that syngeneic cell therapy may potentially be used to ameliorate muscle weakness and delay the progression of XLMTM, as application expands to other muscles.
Asunto(s)
Mioblastos/trasplante , Miopatías Estructurales Congénitas/terapia , Potenciales de Acción , Animales , Modelos Animales de Enfermedad , Femenino , Técnicas de Sustitución del Gen , Genotipo , Inmunohistoquímica , Masculino , Ratones , Ratones Endogámicos C57BL , Músculo Esquelético/citología , Músculo Esquelético/fisiología , Proteína MioD/metabolismo , Mioblastos/citología , Factor 5 Regulador Miogénico/metabolismo , Proteínas Tirosina Fosfatasas no Receptoras/genéticaRESUMEN
BACKGROUND: Doxorubicin (DOX) is associated with premature cardiovascular events including myocardial infarction. This study was performed to determine if the weekly administration of DOX influenced coronary arteriolar medial and/or adventitial wall thickening. METHODS: Thirty-two male Sprague-Dawley rats aged 25.1± 2.4 weeks were randomly divided into three groups and received weekly intraperitoneal injections of normal saline (saline, nâ=â7), or low (1.5 mg/kg to 1.75 mg/kg, nâ=â14) or high (2.5 mg/kg, nâ=â11) doses of DOX. The animals were treated for 2-12 weeks, and euthanized at pre-specified intervals (2, 4, 7, or 10+ weeks) to obtain histopathologic assessments of coronary arteriolar lumen diameter, medial wall thickness, adventitial wall thickness, and total wall thickness (medial thickness + adventitial thickness). RESULTS: Lumen diameter was similar across all groups (saline: 315±34 µm, low DOX: 286±24 µm, high DOX: 242±27 µm; pâ=â0.22). In comparison to animals receiving weekly saline, animals receiving weekly injections of 2.5 mg/kg of DOX experienced an increase in medial (23±2 µm vs. 13±3 µm; pâ=â0.005), and total wall thickness (51±4 µm vs. 36±5 µm; pâ=â0.022), respectively. These increases, as well as adventitial thickening became more prominent after normalizing for lumen diameter (p<0.05 to p<0.001) and after adjusting for age, weight, and total cumulative DOX dose (pâ=â0.02 to pâ=â0.01). Animals receiving low dose DOX trended toward increases in adventitial and total wall thickness after normalization to lumen diameter and accounting for age, weight, and total cumulative DOX dose (pâ=â0.06 and 0.09, respectively). CONCLUSION: In conclusion, these data demonstrate that weekly treatment of rats with higher doses of DOX increases coronary arteriolar medial, adventitial, and total wall thickness. Future studies are warranted to determine if DOX related coronary arteriolar effects are reversible or preventable, exacerbate the known cardiomyopathic effects of DOX, influence altered resting or stress-induced myocardial perfusion, or contribute to the occurrence of myocardial infarction.
Asunto(s)
Antibióticos Antineoplásicos/efectos adversos , Grosor Intima-Media Carotídeo , Vasos Coronarios/efectos de los fármacos , Doxorrubicina/efectos adversos , Animales , Esquema de Medicación , Inyecciones Intraperitoneales , Masculino , Ratas , Ratas Sprague-DawleyRESUMEN
Myogenic tone (MT) is a primary modulator of blood flow in the resistance vasculature of the brain, kidney, skeletal muscle, and perhaps in other high-flow organs such as the pregnant uterus. MT is known to be regulated by endothelium-derived factors, including products of the nitric oxide synthase (NOS) and/or the cyclooxygenase (COX) pathways. We asked whether pregnancy influenced MT in myometrial arteries (MA), and if so, whether such an effect could be attributed to alterations in NOS and/or COX. MA (200-300 µm internal diameter, 2-3 mm length) were isolated from 10 nonpregnant and 12 pregnant women undergoing elective hysterectomy or cesarean section, respectively. In the absence of NOS and/or COX inhibition, pregnancy was associated with increased MT in endothelium-intact MA compared with MA from nonpregnant women (P < 0.01). The increase in MT was not due to increased Ca(2+) entry via voltage-dependent channels since both groups of MA exhibited similar levels of constriction when exposed to 50 mM KCl. NOS inhibition (N(ω)-nitro-L-arginine methyl ester, L-NAME) or combined NOS/COX inhibition (L-NAME/indomethacin) increased MT in MA from pregnant women (P = 0.001 and P = 0.042, respectively) but was without effect in arteries from nonpregnant women. Indomethacin alone was without effect on MT in MA from either nonpregnant or pregnant women. We concluded that MT increases in MA during human pregnancy and that this effect was partially opposed by enhanced NOS activity.
Asunto(s)
Arterias/fisiología , Endotelio Vascular/fisiología , Miometrio/irrigación sanguínea , Óxido Nítrico Sintasa/metabolismo , Prostaglandina-Endoperóxido Sintasas/metabolismo , Vasoconstricción/fisiología , Adulto , Arterias/efectos de los fármacos , Inhibidores de la Ciclooxigenasa/farmacología , Endotelio Vascular/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Indometacina/farmacología , Persona de Mediana Edad , Miometrio/efectos de los fármacos , Miometrio/metabolismo , NG-Nitroarginina Metil Éster/farmacología , Embarazo , Vasoconstricción/efectos de los fármacos , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiologíaRESUMEN
PURPOSE: Botulinum neurotoxin-A (BoNTA) is used to treat several disorders, including Raynaud phenomenon. Recent investigations cite toxin-induced increases in blood flow, but no mechanism for BoNTA's actions is proposed. This study hypothesized that local application of BoNTA causes arteriolar vasodilation through sympathetic blockade and results in increased blood flow. METHODS: Microvascular effects of BoNTA were assessed using a rat cremaster preparation. Cremaster microvascular diameters were measured in the muscle before and after treatment with the muscle paralytic agent gallamine triethiodide. Preparations were then treated with one of the following: BoNTA (4, 6, or 10 units), BoNTA dilution vehicle, or denatured BoNTA. Arteriolar diameters were measured repeatedly over the observation period. Additional preparations were treated with either tetrodotoxin or prazosin and rauwolscine before BoNTA to confirm that the observed vasodilatory responses were the result of sympathetic neural inhibition. RESULTS: The BoNTA application resulted in a significant dose-dependent vasodilation (13% to 15%) of observed cremaster arterioles. Control treatments did not cause vasodilation. Both tetrodotoxin and prazosin/rauwolscine treatments elicited similar vasodilatory effects, with no additional vasodilation elicited by BoNTA. Addition of sodium nitroprusside following BoNTA elicited further vasodilation. In addition, systemic arterial pressure was unaffected by the local administration of BoNTA. CONCLUSIONS: Local application of BoNTA results in arteriolar dilation that yields an approximate 69% increase in blood flow, without changing systemic arterial pressure. A BoNTA-mediated vasodilation through sympathetic blockade is a likely mechanism to explain the increase in blood flow reported after treatment with the toxin. CLINICAL RELEVANCE: The ability of BoNTA to inhibit sympathetic nervous input reduces vasoconstriction, which is the most likely mechanism for improvement seen in Raynaud phenomenon patients following BoNTA injection.
Asunto(s)
Toxinas Botulínicas Tipo A/farmacología , Fármacos Neuromusculares/farmacología , Antagonistas de Receptores Adrenérgicos alfa 2/farmacología , Animales , Relación Dosis-Respuesta a Droga , Humanos , Masculino , Microcirculación/efectos de los fármacos , Prazosina/farmacología , Ratas , Ratas Sprague-Dawley , Flujo Sanguíneo Regional/efectos de los fármacos , Tetrodotoxina/farmacología , Vasodilatación/efectos de los fármacos , Vasodilatación/fisiología , Yohimbina/farmacologíaRESUMEN
BACKGROUND: Niacin is suboptimally used in patients because it causes flushing and erythema. These side effects have been attributed to release of the vasodilating prostaglandin D2, generated in a reaction catalyzed by cyclooxygenase-1. Aspirin reduces but does not completely eliminate these side effects. Because some patients are resistant to its antiplatelet effects, we hypothesized that patients with persistent niacin-induced erythema might be aspirin resistant. METHODS: Platelet function studies (via the use of a whole-blood platelet function aggregometer [VerifyNow; Accumetrics, San Diego, CA] with end points of aspirin reaction unit [ARUs] and P2Y12 reaction units [PRUs]) were performed on 32 healthy, drug-free subjects before and after 324 mg of aspirin. A niacin skin test with the use of topical methylnicotinate was also performed before and after the administration of aspirin. Responses to methyl nicotinate were assessed by a reaction score and by counting the time to first visible redness (TTR). RESULTS: All subjects had an expected decrease in arachidonic acid induced platelet response (ARU 642.8 ± 47.20 before to 431.5 ± 41.1 after aspirin, P < .0001) without a significant change in the PRU. The reaction score and TTR were prolonged by aspirin at methylnicotinate concentrations ≥ 0.001 M. Although no subject had aspirin resistance (defined as ARU > 550), there was considerable variability in skin responses with erythema elicited in all subjects at the greatest concentrations. There was no difference in the ARU for subjects with TTR values above and below the mean, indicating that aspirin resistance does not explain the variation in skin responses to a topical niacin derivative. CONCLUSION: Aspirin resistance is unlikely to be a significant contributor to the persistent erythema and flushing in niacin-treated patients.
Asunto(s)
Aspirina/farmacología , Resistencia a Medicamentos , Eritema/inducido químicamente , Niacina/efectos adversos , Adulto , Plaquetas/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Eritema/sangre , Eritema/etiología , Femenino , Humanos , MasculinoRESUMEN
Although the use of antenatal glucocorticoids has resulted in decreased neonatal morbidity/mortality, recent animal studies have raised concerns regarding adverse effects of these medications on postnatal cardiovascular function. We hypothesized that antenatal betamethasone (Beta) exposure alters cerebral vascular reactivity in adult female sheep. We observed that K-induced constriction was comparable in middle cerebral artery (MCA) from Beta-exposed animals and age-matched controls. Pressure-induced constriction was significantly attenuated in MCA from Beta-exposed compared with control sheep. Inhibition of NOS significantly augmented pressure-induced constriction in MCA from both Beta-exposed and control sheep, whereas cyclooxygenase (COX) inhibition augmented pressure-induced constriction only in MCA from Beta-exposed sheep. Furthermore, NOS and COX inhibition significantly attenuated bradykinin (BK)-induced dilation in MCA from both Beta-exposed and control sheep. However, there seemed to be a greater contribution of both NOS and COX to BK-induced dilation in Beta-exposed compared with control MCA. Our findings demonstrate that fetal exposure to a clinically relevant course of Beta alters cerebral vascular tone and reactivity in adult female sheep.
Asunto(s)
Betametasona/administración & dosificación , Glucocorticoides/administración & dosificación , Arteria Cerebral Media/efectos de los fármacos , Efectos Tardíos de la Exposición Prenatal , Vasoconstricción/efectos de los fármacos , Vasodilatación/efectos de los fármacos , Factores de Edad , Animales , Betametasona/toxicidad , Presión Sanguínea , Inhibidores de la Ciclooxigenasa/farmacología , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Femenino , Glucocorticoides/toxicidad , Arteria Cerebral Media/enzimología , Óxido Nítrico Sintasa/antagonistas & inhibidores , Óxido Nítrico Sintasa/metabolismo , Embarazo , Ovinos , Vasodilatadores/farmacologíaRESUMEN
Nitric oxide (NO) and cyclooxygenase (COX)-derived prostaglandins are critical regulators of the fetal ductus arteriosus. To examine the interaction of these pathways within the ductus wall, the ductus arteriosus of term and preterm fetal mice was evaluated by pressurized myography. The isolated preterm ductus was more sensitive to NOS inhibition than at term. Sequential NOS and COX inhibition caused 36% constriction of the preterm ductus regardless of drug order. In contrast, constriction of the term ductus was dependent on the sequence of inhibition; NOS inhibition prior to COX inhibition produced greater constriction than when inhibitors were given in reverse order (36+/-6% versus 23+/-5%). Selective COX-1 or COX-2 inhibition prior to N(G)-nitro-l-arginine methyl ester (l-NAME) induced the expected degree of constriction. However, NOS inhibition followed by selective COX-2 inhibition caused unexpected ductal dilation. These findings are consistent with NO-induced activation of COX in the ductus arteriosus wall and the production of a COX-2-derived constrictor prostanoid that contributes to the balance of vasoactive forces that maintain fetal ductus arteriosus tone.
Asunto(s)
Conducto Arterial/efectos de los fármacos , Feto/irrigación sanguínea , Óxido Nítrico/metabolismo , Prostaglandina-Endoperóxido Sintasas/metabolismo , Ácido 15-Hidroxi-11 alfa,9 alfa-(epoximetano)prosta-5,13-dienoico/farmacología , Animales , Inhibidores de la Ciclooxigenasa/farmacología , Interacciones Farmacológicas , Femenino , Técnicas In Vitro , Indometacina/farmacología , Ratones , Miografía , NG-Nitroarginina Metil Éster/farmacología , Donantes de Óxido Nítrico/farmacología , Embarazo , Factores de Tiempo , Vasoconstricción/efectos de los fármacos , Vasoconstrictores/farmacología , Vasodilatación/efectos de los fármacosRESUMEN
BACKGROUND/AIMS: The transglutaminases (TG2 and factor XIIIa) may contribute to the stability of arteries by cross-linking a variety of substrates, including extracellular matrix proteins and protease inhibitors. The preferred substrates have never been determined, however. METHODS: We used an amine donor, 5-biotinamidopentylamine, that is covalently linked to acceptor glutamine residues, to determine transglutaminase substrates in carotid endarterectomy tissue. RESULTS: The incorporation of 5-biotinamidopentylamine was calcium dependent, resulting in the labeling of several proteins that were detected by streptavidin-peroxidase and purified over a monomeric avidin affinity column. A major band of 42 kDa that was eluted from the column was sequenced along with 2 additional bands (80 and 65 kDa), revealing an internal fragment of vimentin, transferrin and albumin, respectively. Vimentin dimers were detected in 5 out of 5 carotid plaque homogenates. CONCLUSIONS: Vimentin is a major arterial substrate for transglutaminases. It has previously been shown that TG2 activity and vimentin contribute to vasomotor activity of arteries. Furthermore, transglutaminases (both TG2 and factor XIIIa), as well as vimentin, regulate structural alterations (inward remodeling) that occur in response to low flow states. Transglutaminase-mediated vimentin dimerization produces a novel unifying pathway by which vasodilatory and remodeling responses may be regulated.
Asunto(s)
Arterias Carótidas/metabolismo , Factor XIIIa/metabolismo , Transglutaminasas/metabolismo , Vasodilatación/fisiología , Vimentina/metabolismo , Aminas/metabolismo , Secuencia de Aminoácidos , Biotina/análogos & derivados , Biotina/metabolismo , Biotinilación , Calcio/farmacología , Arterias Carótidas/fisiología , Arterias Carótidas/ultraestructura , Estenosis Carotídea/metabolismo , Dimerización , Endarterectomía Carotidea , Proteínas de Unión al GTP , Hemorreología , Humanos , Datos de Secuencia Molecular , Fragmentos de Péptidos/metabolismo , Proteína Glutamina Gamma Glutamiltransferasa 2 , Alineación de Secuencia , Albúmina Sérica/metabolismo , Especificidad por Sustrato , Transferrina/metabolismo , Vimentina/química , Vimentina/fisiologíaRESUMEN
Leukotrienes are important lipid mediators of asthma that contribute to airway inflammation and bronchoconstriction. Critical mechanisms for physiological regulation of the main G protein-coupled receptor (GPCR) mediating the leukotriene responses in asthma, cysteinyl leukotriene type 1 receptor (CysLT1R), have not been delineated. Although desensitization of GPCRs is a well-established phenomenon, studies demonstrating its physiological relevance are lacking. Here, we demonstrate that relief of PKC-mediated desensitization of endogenous CysLT1Rs augments multiple LTD4-stimulated cellular functions, with associated increases in intracellular signaling events. In analyses of airway smooth muscle contraction ex vivo, PKC inhibition augmented LTD4-stimulated contraction, and increased phosphoinositide hydrolysis and calcium flux in both murine and human airway smooth muscle cells. Similarly, for human monocytes, PKC inhibition augmented LTD4-stimulated calcium flux and cell migration assessed in transwell chamber experiments and also augmented LTD4-induced production of monocyte chemotactic protein assessed by ELISA. In contrast, PKC inhibition had no effect or slightly attenuated these cell functions and signaling events promoted by other receptor agonists, suggesting that despite antithetical effects on downstream events, desensitization of the CysLT1R is the principal mechanism by which PKC regulates the functional consequences of CysLT1R activation.
Asunto(s)
Proteínas de la Membrana/fisiología , Contracción Muscular/fisiología , Proteína Quinasa C/metabolismo , Receptores de Leucotrienos/fisiología , Animales , Calcio/sangre , Quimiocina CCL2/fisiología , Quimiotaxis de Leucocito/fisiología , Humanos , Inhalación/fisiología , Leucotrienos/fisiología , Proteínas de la Membrana/genética , Ratones , Ratones Transgénicos , Monocitos/fisiología , Músculo Liso/fisiología , Fosfatidilinositoles/metabolismo , Reacción en Cadena de la Polimerasa , Receptores de Leucotrienos/genética , Tráquea/fisiologíaRESUMEN
BACKGROUND: P2Y12 is the major platelet receptor that mediates ADP-induced aggregation. P2Y12 is also expressed by vascular cells. The factors that regulate P2Y12 expression have not been determined. Since nicotine (NIC) has effects on platelet activation and vascular function, and because nicotinic and purinerigic receptors may interact, we determined whether nicotine altered P2Y12 expression. METHODS: Four cell lines (human coronary artery endothelial cells, HCAEC; human umbilical vein endothelial cells, HUVEC; human aortic smooth muscle cells, HASMC; and human megakaryoblastic cells, MEG-01) were cultured in the absence or presence of nicotine. Immunoblotting for P2Y12, P2Y2, and actin was performed. RESULTS: Nicotine, at concentrations of 0.1-1.0 microM, induced P2Y12 (but not P2Y2) expression in all the four cell lines. HASMC exhibited the greatest induction with a sixfold mean increase in P2Y12 expression in response to 0.25 microM nicotine. The induction was inhibited by nicotinic acetylcholine receptor antagonists. Healthy smokers were observed to have higher P2Y12 expression in platelet lysates compared to non-smokers. CONCLUSION: Nicotine induces the expression of P2Y12 in vascular cells and megakaryoblasts, and is mediated by nicotinic acetylcholine receptors. Smokers exhibit higher platelet P2Y12, possibly mediated via nicotine. These results may contribute to a better understanding of the effects of cigarette smoking on platelet activation and the vessel wall. CONDENSED ABSTRACT: The factors that regulate the expression of P2Y12, the platelet ADP receptor, have not been determined. Four cell lines (human coronary artery endothelial cells, HCAEC; human umbilical vein endothelial cells, HUVEC; human aortic smooth muscle cells, HASMC; and human megakaryoblastic cells, MEG-01) were cultured in the absence or presence of nicotine. Nicotine, at concentrations of 0.1-1.0 microM, induced P2Y12 expression in all the four cell lines. HASMC exhibited the greatest induction with a sixfold mean increase in P2Y12 expression in response to 0.25 microM nicotine. The induction was inhibited by nicotinic acetylcholine receptor antagonists. Healthy smokers were observed to have higher P2Y12 expression in platelet lysates compared to non-smokers. These results may contribute to a better understanding of the effects of cigarette smoking on platelet activation and the vessel wall.
Asunto(s)
Células Endoteliales/metabolismo , Megacariocitos/metabolismo , Nicotina/farmacología , Agonistas Nicotínicos/farmacología , Receptores Purinérgicos P2/metabolismo , Adulto , Femenino , Humanos , Masculino , Persona de Mediana Edad , Activación Plaquetaria/efectos de los fármacos , Receptores Purinérgicos P2Y12 , Fumar/efectos adversos , Células Tumorales Cultivadas , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Controversy exists concerning whether activation of N-methyl-D-aspartate (NMDA) receptors exerts direct dilator effects on cerebral arteries. The purpose of this study was to examine the responses of isolated piglet arteries to NMDA to determine whether isolated arteries, apart from surrounding neuronal tissue, are capable of responding to NMDA. Piglet arteries (100-200 microm) were isolated from branches of the middle cerebral artery and carefully dissected free of adherent tissue. Arteries were then mounted in an arteriograph system and pressurized to either 30 mm Hg (n=8), 60 mm Hg (n=10), 80 mm Hg (n=6), or 100 mm Hg (n=5). After development of spontaneous tone, NMDA (10(-5) to 10(-3) M) was administered abluminally to the vessels, and no appreciable response was noted (for example; 10(-4) M, 30 mm Hg: 3+/-3% change in active diameter; 60 mm Hg: -4+/-3% change in active diameter). Following a thorough washout, vessels were treated with bradykinin (10(-9) to 10(-7) M), and the arteries did respond (10(-7) M, 30 mm Hg: 26+/-3% change in active diameter; 60 mm Hg: 65+/-10% change in active diameter). In contrast, 10(-5) M and 10(-4) M NMDA dilated arteries in vivo by 9+/-2% and 29+/-6% change in active diameter, respectively (n=6). These results demonstrate that isolated cerebral arteries do not respond directly to NMDA receptor activation. This work confirms our previous in vivo data and is consistent with the hypothesis that cerebral arteries respond to NMDA through a secondary interaction mediated by neuronal release of NO and not to NMDA directly.
Asunto(s)
Arterias Cerebrales/fisiología , Agonistas de Aminoácidos Excitadores/farmacología , N-Metilaspartato/farmacología , Piamadre/irrigación sanguínea , Vasodilatación/efectos de los fármacos , Animales , Animales Recién Nacidos , Arterias/efectos de los fármacos , Bradiquinina/farmacología , Arterias Cerebrales/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Femenino , Técnicas In Vitro , Masculino , Porcinos , Vasodilatadores/farmacologíaRESUMEN
Cysteinyl leukotrienes activate the cysteinyl leukotriene type 1 receptor (CysLT1R) to regulate numerous cell functions important in inflammatory processes and diseases such as asthma. Despite its physiologic importance, no studies to date have examined the regulation of CysLT1R signaling or trafficking. We have established model systems for analyzing recombinant human CysLT1R and found regulation of internalization and signaling of the CysLT1R to be unique among G protein-coupled receptors. Rapid and profound LTD4-stimulated internalization was observed for the wild type (WT) CysLT1R, whereas a C-terminal truncation mutant exhibited impaired internalization yet signaled robustly, suggesting a region within amino acids 310-321 as critical to internalization. Although overexpression of WT arrestins significantly increased WT CysLT1R internalization, expression of dominant-negative arrestins had minimal effects, and WT CysLT1R internalized in murine embryonic fibroblasts lacking both arrestin-2 and arrestin-3, suggesting that arrestins are not the primary physiologic regulators of CysLT1Rs. Instead, pharmacologic inhibition of protein kinase C (PKC) was shown to profoundly inhibit CysLT1R internalization while greatly increasing both phosphoinositide (PI) production and calcium mobilization stimulated by LTD4 yet had almost no effect on H1 histamine receptor internalization or signaling. Moreover, mutation of putative PKC phosphorylation sites within the CysLT1R C-tail (CysLT1RS(313-316)A) reduced receptor internalization, increased PI production and calcium mobilization by LTD4, and significantly attenuated the effects of PKC inhibition. These findings characterized the CysLT1R as the first G protein-coupled receptor identified to date in which PKC is the principal regulator of both rapid agonist-dependent internalization and rapid agonist-dependent desensitization.
Asunto(s)
Proteínas de la Membrana/fisiología , Receptores de Leucotrienos/fisiología , Secuencia de Aminoácidos , Animales , Células COS , Línea Celular , Chlorocebus aethiops , Humanos , Riñón , Cinética , Leucotrieno D4/farmacología , Proteínas de la Membrana/genética , Proteínas de la Membrana/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Conformación Proteica , Transporte de Proteínas , Receptores de Leucotrienos/genética , Receptores de Leucotrienos/metabolismo , Transducción de Señal , TransfecciónRESUMEN
Novel non-thiazolidinedione, tyrosine-derived peroxisome proliferator-activated receptor gamma agonists, GI 262570, GW 7845, GW 1929, developed by GlaxoSmithKline (GSK) along with pioglitazone and nisoldipine, were studied on currents through L-type voltage-dependent calcium channels (VDCC) in freshly isolated smooth muscle cells from mesenteric arteries, and on the diameter of pressurized mesenteric arteries in vitro. Using Ba2+ (10 mmol/l) as the charge carrier through VDCC, the half-inhibition constants (IC50) for GI 262570, GW 7845, GW 1929, and pioglitazone were 2.0 +/- 0.5, 3.0 +/- 0.5, 5.0 +/- 0.7, and 10.0 +/- 0.8 mumol/l, respectively. For arterial diameter measurements the IC50 values for GI 262570, GW 7845, GW 1929, and pioglitazone were 2.4, 4.1, 6.3, and 13.9 mumol/l, respectively. Each GSK compound and pioglitazone was effective at inhibiting VDCC and relaxing pressurized arteries, suggesting that the vasodilation of resistance arteries could be explained by the inhibition of calcium entry through VDCC.
Asunto(s)
Benzofenonas/farmacología , Canales de Calcio/efectos de los fármacos , Hipoglucemiantes/farmacología , Tono Muscular/efectos de los fármacos , Músculo Liso Vascular/efectos de los fármacos , Oxazoles/farmacología , PPAR gamma/agonistas , Tiazolidinedionas/farmacología , Tirosina/análogos & derivados , Tirosina/farmacología , Algoritmos , Animales , Bario/antagonistas & inhibidores , Presión Sanguínea/efectos de los fármacos , Canales de Calcio/metabolismo , Electrofisiología , Femenino , Técnicas In Vitro , Potenciales de la Membrana/efectos de los fármacos , Arterias Mesentéricas/citología , Arterias Mesentéricas/efectos de los fármacos , Células Musculares/efectos de los fármacos , Músculo Liso Vascular/citología , Técnicas de Placa-Clamp , Pioglitazona , Ratas , Ratas Sprague-Dawley , Vasodilatación/efectos de los fármacosRESUMEN
20-Hydroxyeicosatetraenoic acid (20-HETE), a cytochrome p-450 metabolite of arachidonic acid, is a vasoconstrictor in the systemic circulation and a vasodilator in the adult pulmonary circulation. Little is known about the vasoactive properties of 20-HETE in the newborn pulmonary circulation. The objectives of this study were to determine the vascular effects of 20-HETE and to explore the signaling mechanism(s) that mediate these effects in newborn pulmonary resistance-level arteries (PRA). Our findings demonstrate that, in contrast to the adult pulmonary circulation where 20-HETE mediates vasodilation, it causes constriction in newborn PRA at resting tone. Furthermore, inhibition of cyclooxygenase (COX) with indomethacin augments 20-HETE-induced constriction. The enhanced constrictor response to 20-HETE under conditions of COX inhibition is abolished in endothelium-disrupted PRA, suggesting that 20-HETE either stimulates endothelium-derived COX to release a counteracting vasodilator or is rapidly metabolized by COX to a less potent vasoconstrictor. 20-HETE-induced constriction is significantly inhibited by blocking calcium-dependent K(+) (K(Ca)) channels and the thromboxane-PGH(2) receptor. Altogether, our data indicate that the vascular actions of 20-HETE are partially mediated via the activation of K(Ca) channels and are significantly modulated by interactions with the COX-prostaglandin pathway.
Asunto(s)
Ácidos Hidroxieicosatetraenoicos/farmacología , Circulación Pulmonar/efectos de los fármacos , Vasoconstrictores/farmacología , Animales , Animales Recién Nacidos , Endotelio Vascular/efectos de los fármacos , Endotelio Vascular/metabolismo , Microcirculación/efectos de los fármacos , Canales de Potasio/metabolismo , Prostaglandina-Endoperóxido Sintasas/metabolismo , Prostaglandinas/metabolismo , Receptores de Tromboxanos/metabolismo , Receptores de Tromboxano A2 y Prostaglandina H2/metabolismo , Transducción de Señal/efectos de los fármacos , Porcinos , Resistencia Vascular/efectos de los fármacosRESUMEN
The transcription factor NFAT (nuclear factor of activated T-cells) is implicated in cardiac hypertrophy and vasculogenesis. NFAT activation, reflecting dephosphorylation by the calcium-dependent phosphatase, calcineurin, and subsequent nuclear localization, is generally thought to require a sustained increase in intracellular calcium. However, in smooth muscle we have found that elevation of calcium by membrane depolarization fails to induce an increase in nuclear localization of the NFATc3 isoform. Here, we demonstrate that physiological intravascular pressure (100 mm Hg) induces an increase in NFATc3 nuclear localization in mouse cerebral arteries. Pressure-induced NFATc3 nuclear accumulation is abrogated by endothelial denudation and by nitric-oxide synthase, cGMP-dependent kinase (PKG), and voltage-dependent calcium channels inhibition. We further show that exogenous nitric oxide, in combination with an elevation in calcium, is an effective stimulus for NFATc3 nuclear accumulation. c-Jun terminal kinase 2 (JNK) activity, which has been shown to regulate NFATc3 nuclear export, is also reduced by pressure, an effect that is prevented by pretreatment with a PKG inhibitor. Consistent with this, pressure-induced NFATc3 nuclear accumulation is independent of PKG in arteries from JNK2(-/-) mice. Collectively, our results indicate that both activation of the NO/PKG pathway and elevation of smooth muscle calcium are required for NFATc3 nuclear accumulation and that PKG inhibits JNK2 to decrease NFAT nuclear export. Our findings suggest that at physiological intravascular pressures NFATc3 is localized to the nucleus in smooth muscle cells of intact arteries and indicate a novel and unexpected role for nitric oxide/PKG in NFAT activation.
Asunto(s)
Calcio/metabolismo , Núcleo Celular/metabolismo , Proteínas Quinasas Dependientes de GMP Cíclico/metabolismo , Proteínas de Unión al ADN/biosíntesis , Endotelio Vascular/metabolismo , Óxido Nítrico/metabolismo , Factores de Transcripción/biosíntesis , Transporte Activo de Núcleo Celular , Animales , Células Cultivadas , Proteínas Quinasas Dependientes de GMP Cíclico/antagonistas & inhibidores , Masculino , Ratones , Ratones Endogámicos C57BL , Microscopía Fluorescente , Proteína Quinasa 9 Activada por Mitógenos , Proteínas Quinasas Activadas por Mitógenos/metabolismo , Modelos Biológicos , Músculo Liso/embriología , Músculo Liso/metabolismo , Factores de Transcripción NFATC , Óxido Nítrico Sintasa/metabolismo , Fosforilación , Potasio/metabolismo , Presión , Isoformas de Proteínas , Transporte de Proteínas , Factores de TiempoRESUMEN
The endothelium is a critical regulator of vascular tone, and dysfunction of the endothelium contributes to numerous cardiovascular pathologies. Recent studies suggest that apamin-sensitive, small-conductance, Ca2+-activated K+ channels may play an important role in active endothelium-dependent vasodilations, and expression of these channels may be altered in disease states characterized by vascular dysfunction. Here, we used a transgenic mouse (SK3T/T) in which SK3 expression levels can be manipulated with dietary doxycycline (DOX) to test the hypothesis that the level of expression of the SK subunit, SK3, in endothelial cells alters arterial function and blood pressure. SK3 protein was elevated in small mesenteric arteries from SK3T/T mice compared with wild-type mice and was greatly suppressed by dietary DOX. SK3 was detected in the endothelium and not in the smooth muscle by immunohistochemistry. In whole-cell patch-clamp experiments, SK currents in endothelial cells from SK3T/T mice were almost completely suppressed by dietary DOX. In intact arteries, SK3 channels contributed to sustained hyperpolarization of the endothelial membrane potential, which was communicated to the arterial smooth muscle. Pressure- and phenylephrine-induced constrictions of SK3T/T arteries were substantially enhanced by treatment with apamin, suppression of SK3 expression with DOX, or removal of the endothelium. In addition, suppression of SK3 expression caused a pronounced and reversible elevation of blood pressure. These results indicate that endothelial SK3 channels exert a profound, tonic, hyperpolarizing influence in resistance arteries and suggest that the level of SK3 channel expression in endothelial cells is a fundamental determinant of vascular tone and blood pressure.