Williams D A, Huxley V H
Department of Physiology, University of Missouri-Columbia 65212.
Am J Physiol. 1993 May;264(5 Pt 2):H1575-81. doi: 10.1152/ajpheart.1993.264.5.H1575.
Bradykinin, a vasodilator, increases permeability to macromolecules in postcapillary venules. Recent studies indicate that vasodilators elevate water flux from frog mesenteric capillaries. Thus we hypothesized that bradykinin would also increase transcapillary water flux. Arteriolar (ac), true (tc), and venular (vc) capillaries were identified within the microvascular network of frog mesentery. Each capillary was cannulated in situ and perfused with control (frog Ringer and 10 mg/ml bovine serum albumin) and then bradykinin test (10(-7) M) solutions. Hydraulic conductivity (Lp) increased across the network (1.8, 5.3, and 11.0 x 10(-7) cm.s-1.cmH2O-1 for ac, tc, and vc, respectively). Bradykinin test Lp normalized to control (LpBKN/LPC) was elevated threefold (n = 37). Lp for ac (n = 12) was elevated 3.5-fold and oscillated with time. Lp for tc (n = 13) increased fivefold within the first 5 min of exposure and then dropped. Lp for vc (n = 12) was not different from control. Location- and time-dependent responses of Lp indicate that capillaries forming microvascular networks have individual responses to bradykinin.
缓激肽是一种血管舒张剂，可增加毛细血管后微静脉对大分子的通透性。最近的研究表明，血管舒张剂可提高青蛙肠系膜毛细血管的水通量。因此，我们推测缓激肽也会增加跨毛细血管的水通量。在青蛙肠系膜的微血管网络中识别出小动脉毛细血管（ac）、真毛细血管（tc）和微静脉毛细血管（vc）。对每根毛细血管进行原位插管，并用对照溶液（青蛙任氏液和10mg/ml牛血清白蛋白）灌注，然后用缓激肽测试溶液（10⁻⁷M）灌注。整个网络的水力传导率（Lp）均增加（ac、tc和vc的Lp分别为1.8、5.3和11.0×10⁻⁷cm·s⁻¹·cmH₂O⁻¹）。缓激肽测试的Lp相对于对照进行归一化处理（LpBKN/LPC）后升高了三倍（n = 37）。ac的Lp（n = 12）升高了3.5倍，并随时间振荡。tc的Lp（n = 13）在暴露的前5分钟内增加了五倍，然后下降。vc的Lp（n = 12）与对照无差异。Lp的位置和时间依赖性反应表明，形成微血管网络的毛细血管对缓激肽有个体反应。
