Effects of sustained low-flow perfusion on the response to vasoconstrictor agents in postnatal intestine.
Effects of sustained low-flow perfusion on the response to vasoconstrictor agents in postnatal intestine.
复制标题
持续低流量灌注对产后肠道血管收缩剂反应的影响。
DOI：
10.1152/ajpgi.1999.276.6.g1408
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Nowicki,PT
中科院分区：
文献类型：
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作者：
Nowicki,PT
该实验室以前曾报道，新生儿肠道中血流的持续减少导致血管阻力的三相增加，发生在3-4小时内，这些变化部分是由内皮一氧化氮（NO）产生的损失介导的。本研究探讨了暴露于持续低流量灌注对随后对三种收缩激动剂的反应的影响：ANG II，去甲肾上腺素（NE）和内皮素-1（ET-1）。将来自3和35日龄猪的肠环暴露于体内低流量条件（即，将流量降低至基线的50%以上）持续30分钟或5小时。此后，将其移至体外灌注回路进行体外血液动力学评估;或者，取出灌注肠袢的肠系膜动脉并切成环，以评估等长张力发展。暴露于低流量条件下的3日龄受试者的肠袢显示对ANG II、NE和ET-1的收缩反应显著增加;此外，来自这些肠袢的肠系膜动脉环显示所有三种激动剂的ED 50显著降低。在老年受试者的肠或肠系膜动脉环中未观察到类似的变化。持续阻断内源性NO合成与NG-单甲基-L-精氨酸重复暴露于持续低流量灌注的影响。新生儿肠道中血流的持续减少似乎降低了组成型NO的产生，这反过来又导致ANG II、NE和ET-1的收缩功效的普遍增强。
This laboratory has previously reported that sustained reduction of blood flow in newborn intestine causes a triphasic increase in vascular resistance that occurs over 3–4 h and that these changes are mediated, in part, by loss of endothelial nitric oxide (NO) production. This study examines the effects of exposure to sustained low-flow perfusion on the subsequent response to three contractile agonists: ANG II, norepinephrine (NE), and endothelin-1 (ET-1). Gut loops from 3- and 35-day-old swine were exposed to low-flow conditions in vivo (i.e., reduction of flow to ∼50% of baseline) for 30 min or 5 h. Thereafter, they were removed to an extracorporeal perfusion circuit for in vitro hemodynamic assessment; alternatively, the mesenteric artery perfusing the gut loop was removed and cut into rings for assessment of isometric tension development. Gut loops from 3-day-old subjects exposed to low-flow conditions demonstrated significantly increased contractile responses to ANG II, NE, and ET-1; also, mesenteric artery rings from these gut loops demonstrated a significant reduction of the ED50for all three agonists. Similar changes were not observed in intestine or mesenteric artery rings from older subjects. Sustained blockade of endogenous NO synthesis withNG-monomethyl-l-arginine duplicated the effects of exposure to sustained low-flow perfusion. It appears that sustained reduction of blood flow in newborn intestine decreases constitutive NO production, which in turn causes a generalized enhancement of the contractile efficacy of ANG II, NE, and ET-1.