Cassin S, Gause G, Davis T, ter Riet M, Baker R
Department of Physiology, College of Medicine, University of Florida, Gainesville 32610.
J Appl Physiol (1985). 1989 Apr;66(4):1779-84. doi: 10.1152/jappl.1989.66.4.1779.
Lipoxygenase products have been suggested as mediators of the hypoxic pulmonary pressor response in newborn animals. Data supporting this suggestion are equivocal, since lipoxygenase and leukotriene receptor antagonists that have been used may produce vasodilation because of phosphodiesterase inhibition. We used a leukotriene receptor antagonist L 649923, which appears not to have smooth muscle relaxant activity. L 649923 blocks pressor responses to leukotriene D4 (LTD4) without diminishing the pressor response to hypoxia. Also, BW 755C did not block the pressor response to hypoxia in newborn sheep and goats, whereas the pressor response to LTD4 (75 ng/kg) was depressed significantly. In newborn sheep there was an augmented response to hypoxia with BW 755C, which is consistent with cyclooxygenase inhibition. Finally, the thromboxane receptor antagonist SQ 29548 was investigated in both species. With this agent the pressor response to LTD4 in contrast to that of hypoxia was completely inhibited. We conclude that thromboxanes are involved in the pressor response to LTD4 in newborn lambs and goats. These data do not support the view that leukotrienes are involved in the ovine or caprine neonatal pulmonary pressor response to hypoxia.
脂氧合酶产物被认为是新生动物低氧性肺血管收缩反应的介质。支持这一观点的数据并不明确，因为所使用的脂氧合酶和白三烯受体拮抗剂可能由于抑制磷酸二酯酶而产生血管舒张作用。我们使用了一种白三烯受体拮抗剂L 649923，它似乎没有平滑肌舒张活性。L 649923可阻断对白三烯D4（LTD4）的升压反应，而不减弱对低氧的升压反应。此外，BW 755C并未阻断新生绵羊和山羊对低氧的升压反应，而对LTD4（75 ng/kg）的升压反应则显著降低。在新生绵羊中，BW 755C使对低氧的反应增强，这与环氧化酶抑制作用一致。最后，在这两个物种中都研究了血栓素受体拮抗剂SQ 29548。使用该药物后，与低氧反应相反，对LTD4的升压反应被完全抑制。我们得出结论，血栓素参与新生羔羊和山羊对LTD4的升压反应。这些数据不支持白三烯参与绵羊或山羊新生儿对低氧的肺血管收缩反应这一观点。
