Chandler W L, Loo S C, Mornin D
Department of Laboratory Medicine, University of Washington, Seattle 98195.
Thromb Haemost. 1992 Nov 10;68(5):545-9.
The purpose of this study was to determine whether different regions of the rabbit vascular system show variations in the rate of plasminogen activator (PA) secretion. To start, we evaluated the time course, dose response and adrenergic specificity of PA release. Infusion of 1 microgram/kg of epinephrine stimulated a 116 +/- 60% (SD) increase in PA activity that peaked 30 to 60 s after epinephrine administration. Infusion of 1 microgram/kg of norepinephrine, isoproterenol and phenylephrine had no effect on PA activity. Pretreatment with phentolamine, an alpha adrenergic antagonist, blocked the release of PA by epinephrine while pretreatment with the beta blocker propranolol had no effect. This suggests that PA release in the rabbit was mediated by some form of alpha receptor. Significant arterio-venous differences in basal PA activity were found across the pulmonary and splanchnic vascular beds but not the lower extremity/pelvic bed. After stimulation with epinephrine, PA activity increased 46% across the splanchnic bed while no change was seen across the lower extremity/pelvic bed. We conclude that several vascular beds contribute to circulating PA activity in the rabbit, and that these beds secrete PA at different rates under both basal and stimulated conditions.
本研究的目的是确定兔血管系统的不同区域在纤溶酶原激活物（PA）分泌速率上是否存在差异。首先，我们评估了PA释放的时间进程、剂量反应和肾上腺素能特异性。静脉注射1微克/千克肾上腺素可刺激PA活性增加116±60%（标准差），在注射肾上腺素后30至60秒达到峰值。静脉注射1微克/千克去甲肾上腺素、异丙肾上腺素和苯肾上腺素对PA活性无影响。用α肾上腺素能拮抗剂酚妥拉明预处理可阻断肾上腺素诱导的PA释放，而用β受体阻滞剂普萘洛尔预处理则无作用。这表明兔体内PA的释放是由某种形式的α受体介导的。在肺和内脏血管床中发现基础PA活性存在显著的动静脉差异，但在下肢/盆腔血管床中未发现。用肾上腺素刺激后，内脏血管床的PA活性增加了46%，而下肢/盆腔血管床未见变化。我们得出结论，兔体内几个血管床对循环中的PA活性有贡献，并且这些血管床在基础和刺激条件下以不同速率分泌PA。
