Differences in endothelin receptor types in the vasculature of Bothrops jararaca (Viperidae) and Oxyrhopus guibei (Colubridae) snakes

详细信息	查看全文 | 推荐本文 |

• 作者：Lí ; via S.M. Mesquita ; Flá ; via T. Frias ; Eurí ; dice Carmona ; Rosa A.M.B. Borgheresi
• 关键词：Arterial blood pressure ; Bothrops jararaca ; Endothelin ; Endothelin receptors ; Oxyrhopus guibei ; Reptile ; Sarafotoxin ; Snake aorta ; Vascular reactivity
• 刊名：Comparative Biochemistry and Physiology ; Part C
• 出版年：2008
• 期刊代码：8_15320456
• 类别：pha
• 出版时间：July 2008
• 卷：148
• 期：1
• 页码：61-67
• 文件大小：530 K

摘要

Endothelins (ETs) are vasoactive peptides evolutionary well conserved that exert their effects through two specific receptors (ET_A and ET_B) widely distributed in all vertebrates. In snakes, the presence and function of endothelins and their receptors are still scarcely described. We have recently demonstrated the presence of ET_A and ET_B2 receptors in the snake Bothrops jararaca (Bj). In the present work we showed that distinctively from Bj, the vascular contraction induced by endothelin in Oxyrhopus guibei (Og) snake is mediated only by ET_A receptors. Selective ET_B agonists (SRTX-c and IRL₁₆₂₀) and antagonists (IRL₁₀₃₈ and BQ₇₈₈) were ineffective in Og preparations of isolated aorta. We also showed that ET-1 response on Og arterial blood pressure was monophasic hypertensive as opposed to biphasic (hypotension followed by hypertension) in Bj. Furthermore, we characterized the relaxing properties of endothelin receptor ET_B1 in pre-contracted aorta preparations. We showed that IRL₁₆₂₀ induced relaxation of pre-contracted Bj aorta but was ineffective in relaxing Og preparations. IRL₁₆₂₀ relaxing effect on Bj aorta was abolished by l-NAME, indicating involvement of NO release, and was reduced by selective ET_B antagonists. Our findings suggest that Og snake has a more primitive spectrum of ET receptors (only ET_A receptor) than Bj (presence of ET_A, ET_B1 and ET_B2 receptors).