articles+ search results

Physiology, morphology, Physiologie, morphologie, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Vertebres: systeme cardiovasculaire, Vertebrates: cardiovascular system, Vaisseaux sanguins et récepteurs, Blood vessels and receptors, Appareil circulatoire, Circulatory system, Aparato circulatorio, Enzyme, Enzima, Hormone ovarienne, Ovarian hormone, Hormona ovárica, Mammalia, Oxidoreductases, Rodentia, Vaisseau sanguin, Blood vessel, Vaso sanguíneo, Vasomotricité, Vasomotricity, Vasomotricidad, Vertebrata, Artère mésentérique, Mesenteric artery, Arteria mesentérica, Artère rénale, Renal artery, Arteria renal, Azote monoxyde, Nitric oxide, Nitrógeno monóxido, Endothéline, Endothelin, Endothelina, Gestation, Pregnancy, Gestación, Nitric-oxide synthase, Rat, Rata, Relaxine, Relaxin, Relaxina, Récepteur endothéline ETB, ETB endothelin receptor, Receptor endotelina ETB, Vasodilatation, Vasodilation, and Vasodilatación

Administration of the ovarian hormone relaxin to nonpregnant rats vasodilates the renal circulation comparable to pregnancy. This vasodilation is mediated by endothelin (ET), the ETB receptor, and nitric oxide. Furthermore, endogenous relaxin mediates the renal vasodilation and hyperfiltration that occur during gestation. The goal of this study was to investigate whether myogenic reactivity of small renal and mesenteric arteries is reduced in relaxin-treated rats comparable to the pregnant condition. Relaxin or vehicle was administered to virgin female Long-Evans rats for 5 days at 4 μg/h, thereby producing midgestational blood levels of the hormone. The myogenic responses of small renal arteries (200-300 μm in diameter) isolated from these animals were evaluated in an isobaric arteriograph system. Myogenic reactivity was significantly reduced in the small renal arteries from relaxin-treated compared with vehicle-treated rats. The reduced myogenic responses were mediated by the ETB receptor and nitric oxide since the selective ETB receptor antagonist RES-701-1 and the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester restored myogenic reactivity to virgin levels. The influence of relaxin was not limited to the renal circulation because myogenic reactivity was also reduced in small mesenteric arteries isolated from relaxin-treated rats. Thus relaxin administration to nonpregnant rats mimics pregnancy, insofar as myogenic reactivity of small renal and mesenteric arteries is reduced in both conditions.