Endothelium dependence and gestational regulation of inhibition of vascular tone by magnesium sulfate in rat aorta.

摘要: Abstract Objective: The aim of this study was to investigate the role nitric oxide in vasorelaxant effect magnesium sulfate during pregnancy. Study Design: Segments 3 mm aorta, with or without intact endothelium, from 16- 22-day-pregnant rats were mounted organ chambers standard Krebs solution low-magnesium for measurement isometric tension. rings contracted phenylephrine, and cumulative concentration-response curves determined after incubation various inhibitors. Results: Magnesium relaxed aortic pregnant a concentration-dependent manner. relaxation significantly lower on day 22 gestation than 16 gestation. Removal endothelium 10 –4 -mol/L Nω-nitro-L -arginine methyl ester (a synthase inhibitor), –5 6-anilino-5,8-quinolinedione guanylate cyclase indomethacin cyclooxygenase inhibitor) decreased relaxant 16-day-pregnant but not rats. Treatment minimally effective concentrations donor (3 × –10 sodium nitroprusside) cyclic guanosine monophosphate analog (10 –6 8-bromo-cyclic monophosphate) restored response magnesium. Conclusions: rat dependent both gestational age at term late appears potentiate effects through oxide–cyclic systems. (Am J Obstet Gynecol 2001;184:971-8.)