Early in vivo detection of denervation-induced atrophy by luminescence transient nanothermometry.

Denervation induces skeletal muscle atrophy due to the loss of control and feedback with the nervous system. Unfortunately, muscle atrophy only becomes evident days after the denervation event when it could be irreversible. Alternative diagnosis tools for early detection of denervation-induced muscle atrophy are, thus, required. In this work, we demonstrate how the combination of transient thermometry, a technique already used for early diagnosis of tumors, and infrared-emitting nanothermometers makes possible the in vivo detection of the onset of muscle atrophy at short (<1 day) times after a denervation event. The physiological reasons behind these experimental results have been explored by performing three dimensional numerical simulations based on the Pennes' bioheat equation. It is concluded that the alterations in muscle thermal dynamics at the onset of muscle atrophy are consequence of the skin perfusion increment caused by the alteration of peripheral nervous autonomous system. This work demonstrates the potential of infrared luminescence thermometry for early detection of diseases of the nervous system opening the venue toward the development of new diagnosis tools.

Time-dependent dual effect of NLRP3 inflammasome in brain ischaemia.

BACKGROUND: Inflammasomes are cytosolic multiprotein complexes which, upon assembly, activate the maturation and secretion of the inflammatory cytokines IL-1ß and IL-18. However, participation of the NLRP3 inflammasome in ischaemic stroke remains controversial. Our aims were to determine the role of NLRP3 in brain ischaemia, and explore the mechanism involved in the potential protective effect of the neurovascular unit. METHODS: WT and NLRP3 knock-out mice were subjected to ischaemia by middle cerebral artery occlusion (60 min) with or without treatment with MCC950 at different time points post-stroke. Brain injury was measured histologically with 2,3,5-triphenyltetrazolium chloride (TTC) staining. RESULTS: We identified a time-dependent dual effect of NLRP3. While neither the pre-treatment with MCC950 nor the genetic approach (NLRP3 KO) proved to be neuroprotective, post-reperfusion treatment with MCC950 significantly reduced the infarct volume in a dose-dependent manner. Importantly, MCC950 improved the neuro-motor function and reduced the expression of different pro-inflammatory cytokines (IL-1ß and TNF-α), NLRP3 inflammasome components (NLRP3 and pro-caspase-1), protease expression (MMP9), and endothelial adhesion molecules (ICAM and VCAM). We observed a marked protection of the blood-brain barrier (BBB), which was also reflected in the recovery of the tight junction proteins (ZO-1 and Claudin-5). Additionally, MCC950 produced a reduction of the CCL2 chemokine in blood serum and in brain tissue, which lead to a reduction in the immune cell infiltration. CONCLUSIONS: These findings suggest that post-reperfusion NLRP3 inhibition may be an effective acute therapy for protecting the blood-brain barrier in cerebral ischaemia with potential clinical translation.

Uso de Solución Hipertónica en pacientes con insuficiencia cardiaca aguda como terapia adyuvante a altas dosis de diuréticos / Use of Hypertonic Solution in patients with acute heart failure as adjunctive therapy to high-dose diuretics

Resumen La insuficiencia cardíaca aguda descompensada (ICAD) es una causa común de hospitalización, con repercusiones significativas en los sistemas de salud. El manejo agudo se basa en la reducción de la volemia con diuréticos de asa, sin embargo, un porcentaje de pacientes presenta resistencia o no logra la respuesta clínica esperada con este tratamiento. Una de las medidas que ha comprobado ser efectiva en este contexto, es el uso de solución salina hipertónica (SSH) en conjunto con dosis altas de diuréticos de asa, como medida terapéutica temida por sus posibles repercusiones sobre la función renal y posible sobrecarga de sodio. Objetivos: Determinar si el uso de solución salina hipertónica en pacientes con falla cardiaca aguda e hipervolemia genera un deterioro de la función renal. Determinar la respuesta del Pro-BNP ante el uso de la solución salina hipertónica en pacientes con falla cardiaca aguda como marcador de respuesta terapéutica. Determinar si el uso de solución salina hipertónica aumenta la diuresis sin generar cambios importantes en el sodio. Se muestran datos de pacientes con insuficiencia cardiaca aguda descompensada, que tras no presentar mejoría con altas dosis de diurético de asa en bolo, se les aplicó la solución hipertónica como adyuvante a este tratamiento. Se toma un total de 26 pacientes analizando datos generales clínicos y de laboratorio, se valoran curvas con la respuesta diurética y por parámetros de laboratorio a las 48 y 72 horas. El uso de solución salina hipertónica consigue un aumento de más de un 200% de la diuresis en 24 horas, con un descenso del Pro BNP de más de un 60% a las 48 horas, sin mostrar un cambio importante en los niveles de creatinina, nitrógeno ureico y sodio. Se requirió reposición de potasio en la totalidad de los pacientes. Se concluye que la infusión de furosemida más solución hipertónica es efectiva tanto en disminuir niveles de NT Pro-BNP en los pacientes, como en generar un aumento en el volumen de diuresis. La principal complicación fue la hipokalemia, sin cambios considerables en el valor de sodio, creatinina y nitrógeno ureico séricos.

Abstract Uso de Solución Hipertónica en pacientes con insuficiencia cardiaca aguda como terapia adyuvante a altas dosis de diuréticos Acute decompensated heart failure (AHF) is a common cause of hospitalization, with significant repercussions on health systems. Acute management is based on the reduction of blood volume with loop diuretics; however, a percentage of patients show resistance or do not achieve the expected clinical response with this treatment. One of the measures that has proven to be effective in this context is the use of hypertonic saline (HSS) in conjunction with high doses of loop diuretics, as a therapeutic measure feared due to its possible repercussions on kidney function and possible sodium overload. Objetives: To determine if the use of hypertonic saline in patients with acute heart failure and hypervolemia leads to a deterioration in renal function. To determine the response of Pro-BNP to the use of hypertonic saline in patients with acute heart failure as a marker of therapeutic response. Determine if the use of hypertonic saline increases urine output without causing significant changes in sodium. Data are shown from patients with acute decompensated heart failure, who after not presenting improvement with high doses of bolus loop diuretic, the hypertonic solution was applied as an adjunct to this treatment. A total of 26 patients are taken analyzing general clinical and laboratory data, curves with the diuretic response and by laboratory parameters are evaluated at 48 and 72 hours. The use of hypertonic saline solution achieves an increase of more than 200% in diuresis in 24 hours, with a decrease in Pro BNP of more than 60% at 48 hours, without showing a significant change in creatinine levels, urea nitrogen and sodium. Potassium replacement was required in all patients. It is concluded that the infusion of furosemide plus hypertonic solution is effective both in reducing levels of NT Pro-BNP in patients, and in generating an increase in the volume of diuresis. The main complication was hypokalemia, without significant changes in serum sodium, creatinine, and urea nitrogen.

Ultrafast photochemistry produces superbright short-wave infrared dots for low-dose in vivo imaging.

Optical probes operating in the second near-infrared window (NIR-II, 1,000-1,700 nm), where tissues are highly transparent, have expanded the applicability of fluorescence in the biomedical field. NIR-II fluorescence enables deep-tissue imaging with micrometric resolution in animal models, but is limited by the low brightness of NIR-II probes, which prevents imaging at low excitation intensities and fluorophore concentrations. Here, we present a new generation of probes (Ag2S superdots) derived from chemically synthesized Ag2S dots, on which a protective shell is grown by femtosecond laser irradiation. This shell reduces the structural defects, causing an 80-fold enhancement of the quantum yield. PEGylated Ag2S superdots enable deep-tissue in vivo imaging at low excitation intensities (<10 mW cm-2) and doses (<0.5 mg kg-1), emerging as unrivaled contrast agents for NIR-II preclinical bioimaging. These results establish an approach for developing superbright NIR-II contrast agents based on the synergy between chemical synthesis and ultrafast laser processing.

Supplementation with a Carob (Ceratonia siliqua L.) Fruit Extract Attenuates the Cardiometabolic Alterations Associated with Metabolic Syndrome in Mice.

The incidence of metabolic syndrome (MetS) is increasing worldwide which makes necessary the finding of new strategies to treat and/or prevent it. The aim of this study was to analyze the possible beneficial effects of a carob fruit extract (CSAT+®) on the cardiometabolic alterations associated with MetS in mice. 16-week-old C57BL/6J male mice were fed for 26 weeks either with a standard diet (chow) or with a diet rich in fats and sugars (HFHS), supplemented or not with 4.8% of CSAT+®. CSAT+® supplementation reduced blood glucose, Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) and circulating levels of total cholesterol, low-density lipoprotein (LDL) cholesterol (LDL-c), insulin, and interleukin-6 (IL-6). In adipose tissue and skeletal muscle, CSAT+® prevented MetS-induced insulin resistance, reduced macrophage infiltration and the expression of pro-inflammatory markers, and up-regulated the mRNA levels of antioxidant markers. Supplementation with CSAT+® prevented MetS-induced hypertension and decreased the vascular response of aortic rings to angiotensin II (AngII). Moreover, treatment with CSAT+® attenuated endothelial dysfunction and increased vascular sensitivity to insulin. In the heart, CSAT+® supplementation reduced cardiomyocyte apoptosis and prevented ischemia-reperfusion-induced decrease in cardiac contractility. The beneficial effects at the cardiovascular level were associated with a lower expression of pro-inflammatory and pro-oxidant markers in aortic and cardiac tissues.

Effects of age and caloric restriction in the vascular response of renal arteries to endothelin-1 in rats.

Cardiovascular alterations are the most prevalent cause of impaired physiological function in aged individuals with kidney being one the most affected organs. Aging-induced alterations in renal circulation are associated with a decrease in endothelium-derived relaxing factors such as nitric oxide (NO) and with an increase in contracting factors such as endothelin-1(ET-1). As caloric restriction (CR) exerts beneficial effects preventing some of the aging-induced alterations in cardiovascular system, the aim of this study was to analyze the effects of age and caloric restriction in the vascular response of renal arteries to ET-1 in aged rats. Vascular function was studied in renal arteries from 3-month-old Wistar rats fed ad libitum (3m) and in renal arteries from 8-and 24-month-old Wistar rats fed ad libitum (8m and 24m), or subjected to 20% caloric restriction during their three last months of life (8m-CR and 24m-CR). The contractile response to ET-1 was increased in renal arteries from 8m and 24m compared to 3m rats. ET-1-induced contraction was mediated by ET-A receptors in all experimental groups and also by ET-B receptors in 24m rats. Caloric restriction attenuated the increased contraction to ET-1 in renal arteries from 8m but not from 24m rats possibly through NO release proceeding from ET-B endothelial receptors. In 24m rats, CR did not attenuate the aging-increased response of renal arteries to ET-1, but it prevented the aging-induced increase in iNOS mRNA levels and the aging-induced decrease in eNOS mRNA levels in arterial tissue. In conclusion, aging is associated with an increased response to ET-1 in renal arteries that is prevented by CR in 8m but not in 24m rats.

In Vivo Ischemia Detection by Luminescent Nanothermometers.

There is an urgent need to develop new diagnosis tools for real in vivo detection of first stages of ischemia for the early treatment of cardiovascular diseases and accidents. However, traditional approaches show low sensitivity and a limited penetration into tissues, so they are only applicable for the detection of surface lesions. Here, it is shown how the superior thermal sensing capabilities of near infrared-emitting quantum dots (NIR-QDs) can be efficiently used for in vivo detection of subcutaneous ischemic tissues. In particular, NIR-QDs make possible ischemia detection by high penetration transient thermometry studies in a murine ischemic hindlimb model. NIR-QDs nanothermometers are able to identify ischemic tissues by means of their faster thermal dynamics. In addition, they have shown to be capable of monitoring both the revascularization and damage recovery processes of ischemic tissues. This work demonstrates the applicability of fluorescence nanothermometry for ischemia detection and treatment, as well as a tool for early diagnosis of cardiovascular disease.

Altered expression of P2Y2 and P2X7 purinergic receptors in the isolated rat heart mediates ischemia-reperfusion injury.

The aim of this study is to analyze the expression of purinergic receptors in the heart after ischemia-reperfusion, and their possible role in ischemia-reperfusion injury. Rat hearts were perfused according to the Langendorff technique and subjected to 30 min ischemia followed by 15 min reperfusion. Ischemia-reperfusion reduced the gene expression and protein content of purinergic receptors of the P2Y2 subtype, and increased the gene expression and protein content of the P2X7 subtype. Treatment with the agonist of the P2Y2 subtype 2-thio-UTP and with the antagonist of the P2X7 subtype Brilliant Blue improved myocardial function parameters, reduced cell death and increased the myocardial expression of antiapoptotic markers after ischemia-reperfusion. These results suggest that the myocardial expression of the protective P2Y2 subtype of purinergic receptors is reduced, whereas that of the harmful subtype P2X7 subtype is increased during coronary ischemia-reperfusion. This may contribute to myocardial injury in this condition.

Effects of age and caloric restriction on the cardiac and coronary response to endothelin-1 in rats.

BACKGROUND AND AIMS: Aging is associated with alterations in the cardiovascular system such as increased vasoconstriction and decreased vasodilatation. Some of these changes are partially reversed by caloric restriction. Endothelin-1 is a potent vasoconstrictor which levels increased with age. The aim of this study is to analyze the role of endothelin-1 in the cardiac and coronary changes induced by age and whether these changes may be attenuated by a three-month caloric restriction. METHODS AND RESULTS: Hearts from young (3 months old), aged (24 months old) and aged rats after 3 months of caloric restriction were perfused according to the Langendorff technique. Coronary vasoconstriction to endothelin-1 was reduced in old rats, and endothelin-1 increased myocardial contractility (dP/dt) and heart rate in old but not in young rats. These changes observed in old rats were partly reversed by caloric restriction. Also, in the myocardial tissue of old rats the gene expression of endothelin-1, inducible nitric oxide synthase (iNOS) and tumor necrosis factor alpha (TNF-a) was increased, and the gene expression of endothelin ETB receptors and endothelial nitric oxide syntase (eNOS) was reduced, compared with young rats. Aging induced changes in the expression of ETB receptors and eNOS were reversed by caloric restriction. CONCLUSIONS: These results suggest that aging produces alterations in myocardial and coronary responses to endothelin-1, that may be related to changes in expression of nitric oxide synthases and/or endothelin receptor subtypes, with some of these changes being prevented by caloric restriction.

Purinergic component in the coronary vasodilatation to acetylcholine after ischemia-reperfusion in perfused rat hearts.

To determine the involvement of purinergic receptors in coronary endothelium-dependent relaxation, the response to acetylcholine (1 × 10(-8) to 3 × 10(-7)M) was recorded in isolated rat hearts perfused according to the Langendorff procedure before and after 30 min of ischemia and 15 min of reperfusion and after the inhibition of nitric oxide synthesis with L-NAME (10(-4)M), in the absence and presence of the antagonist of purinergic P2X receptors, PPADS (3 × 10(-6)M), and of the antagonist of purinergic P2Y receptors, Reactive Blue 2 (3 × 10(-7)M). In control conditions, the relaxation to acetylcholine was not altered by PPADS or Reactive Blue 2. The relaxation to acetylcholine was reduced after ischemia-reperfusion, and, in this condition, it was further reduced by treatment with PPADS or Reactive Blue 2. Likewise, the relaxation to acetylcholine was reduced by L-NAME, and reduced further by Reactive Blue 2 but not by PPADS. These results suggest that the relaxation to acetylcholine may be partly mediated by purinergic receptors after ischemia-reperfusion, due to the reduction of nitric oxide release in this condition.

Long-term effects of early overnutrition in the heart of male adult rats: role of the renin-angiotensin system.

To analyze the long-term effects of early overfeeding on the heart and coronary circulation, the effect of ischemia-reperfusion (I/R) and the role of the renin-angiotensin system (RAS) was studied in isolated hearts from control and overfed rats during lactation. On the day of birth litters were adjusted to twelve pups per mother (controls) or to three pups per mother (overfed). At 5 months of age, the rats from reduced litters showed higher body weight and body fat than the controls. The hearts from these rats were perfused in a Langendorff system and subjected to 30 min of ischemia followed by 15 min of reperfusion (I/R). The myocardial contractility (dP/dt) and the coronary vasoconstriction to angiotensin II were lower, and the expression of the apoptotic marker was higher, in the hearts from overfed rats compared to controls. I/R reduced the myocardial contractily, the coronary vasoconstriction to angiotensin II and the vasodilatation to bradykinin, and increased the expression of (pro)renin receptor and of apoptotic and antiapoptotic markers, in both experimental groups. I/R also increased the expression of angiotensinogen in control but not in overfed rats. In summary, the results of this study suggest that early overnutrition induces reduced activity of the RAS and impairment of myocardial and coronary function in adult life, due to increased apoptosis. Ischemia-reperfusion produced myocardial and coronary impairment and apoptosis, which may be related to activation of RAS in control but not in overfed rats, and there may be protective mechanisms in both experimental groups.

Tyrosine phosphorylation modulates the vascular responses of mesenteric arteries from human colorectal tumors.

The aim of this study was to analyze whether tyrosine phosphorylation in tumoral arteries may modulate their vascular response. To do this, mesenteric arteries supplying blood flow to colorectal tumors or to normal intestine were obtained during surgery and prepared for isometric tension recording in an organ bath. Increasing tyrosine phosphorylation with the phosphatase inhibitor, sodium orthovanadate produced arterial contraction which was lower in tumoral than in control arteries, whereas it reduced the contraction to noradrenaline in tumoral but not in control arteries and reduced the relaxation to bradykinin in control but not in tumoral arteries. Protein expression of VEGF-A and of the VEGF receptor FLT1 was similar in control and tumoral arteries, but expression of the VEGF receptor KDR was increased in tumoral compared with control arteries. This suggests that tyrosine phosphorylation may produce inhibition of the contraction in tumoral mesenteric arteries, which may increase blood flow to the tumor when tyrosine phosphorylation is increased by stimulation of VEGF receptors.

Effects of coronary ischemia-reperfusion in a rat model of early overnutrition. Role of angiotensin receptors.

BACKGROUND: Obesity during childhood has dramatically increased worldwide in the last decades. Environmental factors acting early in life, including nutrition, play an important role in the pathogenesis of obesity and cardiovascular diseases in adulthood. AIMS: To analyze the effects of early overfeeding on the heart and coronary circulation, the effect of ischemia-reperfusion (I/R) and the role of the renin-angiotensin system (RAS) were studied in isolated hearts from control and overfed rats during lactation. METHODS AND RESULTS: On the day of birth litters were adjusted to twelve pups per mother (control) or to three pups per mother (overfed). At weaning (21 days) the rats were killed and the heart perfused in a Langendorff system and subjected to 30 min of ischemia followed by 15 min of reperfusion. The contractility (left developed intraventricular pressure) was lower in the hearts from overfed rats, and was reduced by I/R in hearts from control but not from overfed rats. I/R also reduced the coronary vasoconstriction to angiotensin II more in hearts from control than from overfed rats, and the vasodilatation to bradykinin similarly in both experimental groups. The expression of both angiotensin AGTRa and AGTR2 receptors was increased in the myocardium of overfed rats, and I/R increased the expression of both receptors in control rats but reduced it in overfed rats. The expression of apoptotic and antiapoptotic markers was increased in hearts of overfed rats compared with control, and further increased by I/R. CONCLUSIONS: These results suggest that both overfeeding and I/R impair cardiac and coronary function due, at least in part, to activation of the angiotensin pathway. However, overfeeding may reduce the impairment of ventricular contractility by I/R.

Coronary response to diadenosine triphosphate after ischemia-reperfusion in the isolated rat heart.

Diadenosine triphosphate (Ap3A) is a vasoactive mediator stored in platelet granules that may be released during coronary ischemia-reperfusion. To study its coronary effects in such circumstances, rat hearts were perfused in a Langendorff preparation and the coronary response to Ap3A (10(-7)-10(-5) mol/L) was recorded. Both at basal coronary resting tone and after precontraction with 11-dideoxy-1a,9a-epoxymethanoprostaglandin F(2)(α) (U46619), Ap3A produced concentration-dependent vasodilation in the heart, which was attenuated following ischemia-reperfusion. Ap3A-induced relaxation was also attenuated in control conditions and after ischemia-reperfusion by the purinergic P2Y antagonist reactive blue 2 (2 × 10(-6) mol/L), the P2Y(1) antagonist MRS 2179 (10(-5) mol/L), the nitric oxide synthesis inhibitor N-omega-nitro-l-arginine methyl ester (l-NAME; 10(-4) mol/L) and the ATP-dependent potassium channel blocker glibenclamide (10(-5) mol/L). These results suggest that Ap3A induces coronary vasodilation, an effect attenuated by ischemia-reperfusion due to the functional impairment of purinergic P2Y receptors and K(ATP) channels, and/or reduced nitric oxide release. This impairment of vasodilation may contribute to the coronary dysregulation that occurs during ischemia-reperfusion.

Nitric oxide-mediated relaxation to lactate of coronary circulation in the isolated perfused rat heart.

The objective of this study was to analyze the effects of lactate on coronary circulation. Rat hearts were perfused in a Langendorff preparation, and the coronary response to lactate (3-30 mM) was recorded after precontracting coronary vasculature with 11-dideoxy-1a,9a-epoxymethanoprostaglandin F2α (U46619), in the presence or the absence of the inhibitor of nitric oxide synthesis, N-omega-nitro-l-arginine methyl ester (l-NAME, 10 M), the blocker of Ca-dependent potassium channels, tetraethylammonium (TEA, 10 M), or the blocker of adenosine triphosphate-sensitive potassium channels, glybenclamide (10 M). The effects of lactate were also studied in isolated segments of rat coronary arteries that were precontracted with U46619, with or without endothelium. In perfused hearts, lactate induced concentration-dependent coronary vasodilatation and a reduction in myocardial contractility (left ventricular developed pressure and dP/dt) without altering the heart rate. Coronary vasodilatation in response to lactate was reduced by l-NAME but unaffected by TEA or glybenclamide. The effects of lactate on myocardial contractility were unchanged by l-NAME, TEA, or glybenclamide. In isolated coronary artery segments, lactate also produced relaxation, an effect attenuated by removing the endothelium. Together these findings suggest that lactate exerts coronary vasodilatory effects through the release of endothelial nitric oxide, independently of potassium channels. These findings may be relevant for the regulation of coronary circulation when lactate levels are elevated.

Coronary response to diadenosine tetraphosphate after ischemia-reperfusion in the isolated rat heart.

Diadenosine tetraphosphate (AP4A) is a vasoactive mediator that may be released from platelet granules and that may reach higher plasma concentrations during coronary ischemia-reperfusion. The objective of this study was to analyze its coronary effects in such conditions. To this, rat hearts were perfused in a Langendorff preparation and the coronary response to Ap4A (10(-7)-10(-5) M) was recorded. In control hearts, Ap4A produced concentration-dependent vasodilatation both at the basal coronary resting tone and after precontracting coronary vasculature with 11-dideoxy-1a,9a-epoxymethanoprostaglandin F2α (U46619), and this vasodilatation was reduced by reactive blue 2 (2×10(-6) M), glibenclamide (10(-5) M), H89 (10(-6) M), U73122 (5×10(-6) M) and endothelin-1 (10(-9) M), but not by L-NAME (10(-4) M), isatin (10(-4) M), GF109203x (5×10(-7) M), or wortmannin (5×10(-7) M). After ischemia-reperfusion, the vasodilatation to Ap4A diminished, both in hearts with basal or increased vascular tone, and in this case the relaxation to Ap4A was not modified by reactive blue 2, L-NAME, glibenclamide, isatin, H89, GF109203x or wortmannin, although it was reduced by U73122 and endothelin-1. UTP produced coronary relaxation that was also reduced after ischemia-reperfusion. These results suggest that the coronary relaxation to Ap4A is reduced after ischemia-reperfusion, and that this reduction may be due to impaired effects of KATP channels and to reduced response of purinergic P2Y receptors.

Role of alpha-adrenoceptors and prostacyclin in the enhanced adrenergic reactivity of goat cerebral arteries after ischemia-reperfusion.

To analyze ischemia-reperfusion effects on the cerebrovascular adrenergic response, the left middle cerebral artery (MCA) of anesthetized goats was occluded for 120 min and reperfused for 60 min. Isolated segments from the left (ischemic) and right (control) MCA exhibited isometric constriction in response to noradrenaline (10(-8)-10(-4)M, in the presence of beta-adrenoceptors blockade), phenylephrine (alpha(1)-adrenoceptors agonist, 10(-8)-10(-4)M), B-HT-920 (alpha(2)-adrenoceptors agonist, 10(-7) - 3 x 10(-3)M) or tyramine (indirect sympatheticomimetic amine, 10(-8)-10(-4)M), but this constriction was greater in ischemic arteries. The cyclooxygenase (COX) inhibitor meclofenamate (10(-5)M) augmented the response to noradrenaline only in control arteries. The prostacyclin (PGI(2)) synthesis inhibitor tranylcypromine (TCP, 10(-5)M) increased the response to noradrenaline in control arteries and reduced it in ischemic arteries. The thromboxane A(2) (TXA(2)) synthase inhibitor furegrelate (10(-6)M) did not modify the noradrenaline effect in both types of arteries, whereas the TXA(2) receptor antagonist SQ 29 548 (10(-5)M) and the COX-2 inhibitor NS-398 (10(-6)M) decreased the response to noradrenaline only in ischemic arteries. PGI(2) caused a small relaxation in control arteries and a small contraction in ischemic arteries. alpha-Adrenoceptors and COX-2 protein expression and the metabolite of PGI(2) were augmented in ischemic arteries. Therefore, ischemia-reperfusion may increase the cerebrovascular responsiveness to noradrenaline, through upregulation of alpha-adrenoceptors and increased COX-2-derived PGI(2) exerting a vasoconstrictor action. After ischemia-reperfusion, noradrenaline might increase PGI(2) production thus contributing to adrenergic vasoconstriction and/or PGI(2) would potentiate the noradrenaline effects.

Modelo experimental para el estudio de la ascitis en perros / Experimental model for the study of ascites in dogs

La investigación se realizó en Universidad Hermilio Valdizán de Huánuco-Perú, con la finalidad de hacer uniforme el modelo experimental para el estudio de la ascitis en el perro, mediante la disminución del calibre de la vena cava posterior, utilizando anillos preparados ad hoc a partir de sondas rectales de silicona flexible y de dar a conocer los cambios de las proteínas plasmásticas y del líquido ascítico durante la instauración del síndrome ascítico. El estudio se realizó en 05 animales aparentemente sanos de diferente edad, sexo y peso. En el 100 por ciento de los animales presentaron la ascitis a los 13,2 días más menos 4,1 y con un incremento del perímetro abdominal promedio de 63,4 cms. más menos 1,5 con respecto al control basal preoperatorio de 53 cms. más menos 1,2 y no ocurriendo muerte alguna. El comportamiento de las proteínas plasmáticas resultó en una disminución promedio cuando presentaron la ascitis de 3,30 g/dl más menos 0,32 con respecto a los valores encontrados en el preoperatorio 4,89 g/dl más menos 0,35, con la fracción albúmina de 2,00 g/dl más menos 0,91, la que disminuyó con respecto al nivel basal de 2,98 g/dl más menos 0,35 (p menos o igual que 0,05), la globulina incrementó en promedio en los animales con síndrome ascítico de 1,71 g/dl más menos 0,66 a 1,90 g/dl más menos 0,31, mientras que las proteínas totales fue de 3.30 g/dl más menos 0,32 en los animales con ascitis frente a 4,89 g/dl más menos 1,20 que presentaron en el preoperatorio. Se considera este modelo versátil y práctico para el estudio de la ascitis experimental en el perro, reduciendo la mortalidad, además de acortar el tiempo para su obtención cuando se compara con los resultados por otros médicos quirúrgicos.

The research was carried out at the Hermilio Valdizan University Huánuco - Peru, in order to make uniform the experimental model for the study of ascites in dogs, by reducing the size of the posterior vein cava, using ad hoc rings prepared from rectal probe and flexible silicone to make knowing the changes of plasma proteins and ascetic fluid during the installation of ascites. The study was conducted in 05 apparently healthy animals of different age, sex and height. In 100 per cent of the animals had ascites to 13.2 days more less 4.1 and with an increase of the abdominal average perimeter of 63,4 cm with regard to the basal preoperative control of 53 cms. more less 1.2 and not happening any death in the animals. The behavior of plasmatic proteins resulted in an average decrease when they presented the ascites of 3.30 g/dl more less 0.32 with respect to preoperative found values in the 4.89 g/dl more less 0.345 with the fraction albumin 2.00 g/dl more less 0.91, which declined from the basal level of 2.98 g/dl more less 0.35 (p less or equal than 0.05), globulin increased on average in animals with ascites as opposed to 4.89 g / more less 1.20 dl, who presented preoperatively. It is considered as a versatile and practical model for the study of experimental ascites in dogs, it is reduced the mortality, in addition to shortening the time it was obtained when it is compared with the results of other surgical methods.

Effects of endothelin-1 on the relaxation of rat coronary arteries.

To analyze the effects of endothelin-1 on the b-adrenergic response of the coronary circulation, 2-mm-long segments of coronary arteries from rats were prepared for isometric tension recording in organ baths. The relaxation to isoproterenol (3 x 10(-8) M), field electrical stimulation (4 Hz, 0.1-millisecond duration, 10 seconds), acetylcholine (3 x 10(-8) M), and sodium nitroprusside (10(-9) M) was recorded in arteries precontracted with U46619 (10(-7) to 5 x 10(-7) M) before and after treatment with endothelin-1 (3 3 10210 and 1029 M). The relaxation to isoproterenol was increased by treatment with endothelin-1 and with the endothelin ET(B) antagonist BQ788 (10(-6) M) but not with the endothelin ET(A) antagonist BQ123 (10(-6) M) or with the blocker of protein kinase C chelerythrine (10(-5) M). In the presence of BQ788, BQ123, or chelerythrine, endothelin-1 did not modify the relaxation to isoproterenol. Treatment with endothelin-1 did not modify the relaxation to electrical stimulation, acetylcholine, or sodium nitroprusside. These results suggest that endothelin-1 may potentiate coronary beta-adrenergic vasodilatation, at least in part due to stimulation of endothelin ET(A) receptors and activation of protein kinase C.

Role of angiotensin II in the response to endothelin-1 of goat cerebral arteries after ischemia-reperfusion.

As angiotensin II may underlie the deleterious effects of some vascular diseases, we have examined the role of this peptide on the cerbrovascular endothelin-1 action after ischemia-reperfusion. In anesthetized goats, 1 hour-occlusion followed by 1 hour-reperfusion of the left middle cerebral artery (MCA) was induced, and then segments 3-mm in length from branches of the right MCA (control) and the left MCA (ischemic) were obtained for isometric tension recording. Endothelin-1 (10(-11)-10(-7) M) produced a contraction that was higher in ischemic than in control arteries, and in control but not in ischemic arteries this contraction was potentiated by angiotensin II (10(-7) M). Losartan (3 x 10(-6) M), antagonist of AT1 receptors, did not affect the response to endothelin-1 in control arteries, but reduced it both in ischemic arteries and angiotensin II-treated control arteries. PD123,319 (3 x 10(-6) M), antagonist of AT2 receptors, or the inhibitor of nitric oxide synthesis L-NAME (10(-4) M) did not alter the arterial effects of endothelin-1. Therefore, angiotensin II may potentiate the constriction to endothelin-1 in normal cerebral arteries by activating AT1 receptors. The observed cerebrovascular increased response to endothelin-1 after ischemia-reperfusion might be related in part to activation of AT1 receptors under this condition.