Heat stress alters G-protein coupled receptor-mediated function and endothelium-dependent relaxation in rat mesenteric artery.
Heat stress has been demonstrated to have strong cardiovascular effects. However, the underlying mechanism-mediated cardiovascular effects are still not fully understood. The present study was designed to examine if heat stress alters vascular G-protein coupled receptor-mediated vasomotion and endothelium function in rat mesenteric artery. Rats were divided into two groups, heat stress rats and control. The G-protein coupled receptors of endothelin type B (ETB) receptor-, endothelin type A (ETA) receptor-, 5-hydroxytryptamine (5-HT) receptor-, calcitonin gene-related peptide (CGRP) receptor-, alpha-adrenoceptor-mediated vosoactivity and endothelium-dependent relaxation on rat mesenteric artery ring segments were monitored by a myograph system. The plasma level of CGRP was determined by radioimmunological assay. Compared with control arterial segments, the contractile response curves of sarafotoxin 6c, a selective ETB receptor agonist and 5-HT in the arterial segments from heat stress rats were shifted towards left. An increased maximum contraction (Emax) induced by sarafotoxin 6c, but not 5-HT, was seen in the arterial segments from heat stress rats. CGRP-induced relaxation in endothelium-denuded arterial segments from heat stress rats was enhanced. The relaxation in endothelium-intact arterial segments induced by acetylcholine was significantly decreased in heat stress rats. In addition, the plasma concentration of CGRP was increased in heat stress rats. The endothelium-dependent relaxation was characterized and shown there was a decrease in nitric oxide and endothelium-derived hyperpolarizing factor-mediated relaxation in the arterial segments from heat stress rats. In conclusion, heat stress induces an enhanced vascular endothelin ETB-, 5-HT-receptors-mediated contraction, an enhanced CGRP-receptor-induced relaxation and damage to endothelium-dependent relaxation.
Department of Pharmacology, Xi'an Jiaotong University College of Medicine, Xi'an, Shaanxi 710061, PR China.
Jie
J
Li
Yong-Xiao
YX
Cao
Lei
L
Cao
Yong
Y
Liu
Cang-Bao
CB
Xu
D000818:Animals; D001685:Biological Factors / Q000502:physiology; D015740:Calcitonin Gene-Related Peptide / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000502:physiology*; D006358:Hot Temperature; D066298:In Vitro Techniques; D008638:Mesenteric Arteries / Q000502:physiology*; D009569:Nitric Oxide / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017466:Receptors, Endothelin / Q000502:physiology; D043562:Receptors, G-Protein-Coupled / Q000502:physiology*; D011985:Receptors, Serotonin / Q000502:physiology; D014664:Vasodilation
D001685:Biological Factors; D017466:Receptors, Endothelin; D043562:Receptors, G-Protein-Coupled; D011985:Receptors, Serotonin; C067410:endothelium-dependent hyperpolarization factor; D009569:Nitric Oxide; D015740:Calcitonin Gene-Related Peptide