Mehta J L, Lawson D L, Nicolini F A, Ross M H, Player D W
Department of Medicine, University of Florida College of Medicine, Gainesville.
Am J Physiol. 1991 Aug;261(2 Pt 2):H327-34. doi: 10.1152/ajpheart.1991.261.2.H327.
Unstimulated polymorphonuclear leukocytes (PMNLs) release nitric oxide or a like material that relaxes vascular tissues. To determine the effects of activated PMNLs on vascular tone, precontracted rat aortic rings were exposed to ionophore A23187-treated PMNLs. Whereas "unstimulated" PMNLs caused 29 +/- 4% relaxation, "stimulated" PMNLs caused initial contraction followed by 90 +/- 7% relaxation of aortic rings. Indomethacin or the 5-lipoxygenase blocker piriprost had no effect on PMNL-induced initial contraction or subsequent relaxation. However, initial contraction was abolished and the subsequent vasorelaxation attenuated (22 +/- 5%) by the superoxide radical scavenger superoxide dismutase (SOD), suggesting that release of superoxide radicals may have induced vascular contraction and caused endothelial damage that would permit unopposed vasorelaxant effect of PMNLs. To examine this hypothesis, aortic rings were exposed to superoxide radicals (generated by xanthine plus xanthine oxidase, X + XO) or manually deendothelialized. These rings revealed marked relaxation (78 +/- 6 and 85 +/- 6%, respectively) in response to unstimulated PMNLs. These observations suggest that stimulated PMNLs exert an initial vasoconstrictor effect and a subsequent vasorelaxant effect in response to release of superoxide radicals and nitric oxide, respectively. Arachidonate metabolites or 5-lipoxygenase products do not appear to be important in the actions of PMNLs on vascular smooth muscle.
未受刺激的多形核白细胞（PMNLs）释放一氧化氮或类似物质，可使血管组织舒张。为了确定活化的PMNLs对血管张力的影响，将预先收缩的大鼠主动脉环暴露于经离子载体A23187处理的PMNLs中。“未受刺激的”PMNLs可使主动脉环舒张29±4%，而“受刺激的”PMNLs则先引起收缩，随后使主动脉环舒张90±7%。吲哚美辛或5-脂氧合酶阻滞剂匹罗普斯对PMNLs诱导的初始收缩或随后的舒张均无影响。然而，超氧化物自由基清除剂超氧化物歧化酶（SOD）可消除初始收缩，并减弱随后的血管舒张作用（22±5%），这表明超氧化物自由基的释放可能诱导了血管收缩，并导致内皮损伤，从而使PMNLs的血管舒张作用不受拮抗。为了验证这一假设，将主动脉环暴露于超氧化物自由基（由黄嘌呤加黄嘌呤氧化酶产生，X+XO）或手动去内皮。这些环对未受刺激的PMNLs显示出明显的舒张作用（分别为78±6%和85±6%）。这些观察结果表明，受刺激的PMNLs分别对超氧化物自由基和一氧化氮的释放产生初始血管收缩作用和随后的血管舒张作用。花生四烯酸代谢产物或5-脂氧合酶产物在PMNLs对血管平滑肌的作用中似乎并不重要。
