Regional differences in endothelium‐dependent relaxation in the rat: contribution of nitric oxide and nitric oxide‐independent mechanisms

摘要: Relaxant effects of acetylcholine (ACh), histamine, calcitonin gene‐related peptide (CGRP) and the calcium ionophore A23187 were examined in rat femoral (O ≅ 0.2 mm), mesenteric (0.2 intrarenal mm) hepatic (0.3 arteries, aorta (2 mm). Acetylcholine elicited an endothelium‐dependent relaxation all arteries. Histamine induced aorta, whereas a partly mainly endothelium‐independent was observed respectively. In hepatic, CGRP relaxation, either small or no obtained arteries artery, had relaxant effect femoral, Nω‐nitro‐l‐arginine (l‐NOARG, 0.3 mM) reduced maximum ACh‐induced (in presence 10 μM indomethacin) by 66% abolished A marked l‐NOARG/indomethacin‐resistant Levcromakalim concentration‐dependent almost complete When contracted 60 mM K+ solution, responded to ACh with that l‐NOARG. These results demonstrate regional differences regard vascular ACh, A23187. Whereas nitric oxide appears mediate endothelium‐ dependent regardless region, presumably mediated endothelium‐derived hyperpolarizing factor, only aorta. (Less)