Green R S, Lasker M R, McDonnell F E, Holzman I R
Department of Pediatrics, Mount Sinai School of Medicine, New York, N.Y.
Dev Pharmacol Ther. 1992;18(1-2):26-38.
We examined the effect of the alpha 1-adrenergic antagonist prazosin on blood pressure, left ventricular output and blood flow redistribution during normoxemia and mild hypoxemia in the chronically instrumented, unanesthetized newborn piglet employing the radiolabeled microsphere technique. Prior to prazosin, hypoxemia caused increases in aortic pressure and blood flows to the brain, myocardium and diaphragm, accomplished by small, statistically insignificant decreases in flows to the carcass and viscera without an increase in cardiac index. Prazosin treatment during normoxemia caused a fall in blood pressure and resulted in greater blood flows of left ventricular origin to the carcass, myocardium and lung. Hypoxemia after prazosin administration increased not only aortic pressure and blood flows to the brain, myocardium and diaphragm, but also, unlike the situation before drug treatment, cardiac index. Thus, in the newborn piglet, the maintenance of critical organ oxygen delivery during hypoxemia is not blocked by prazosin, but is accomplished by an increase in cardiac index rather than simply by redistribution of blood flow.
我们采用放射性微球技术，在长期植入仪器且未麻醉的新生仔猪中，研究了α1肾上腺素能拮抗剂哌唑嗪在常氧血症和轻度低氧血症期间对血压、左心室输出量及血流重新分布的影响。在使用哌唑嗪之前，低氧血症会导致主动脉压升高以及流向脑、心肌和膈肌的血流量增加，这是通过流向躯体和内脏的血流量小幅下降（统计学上无显著意义）实现的，且心脏指数未增加。常氧血症期间给予哌唑嗪治疗会导致血压下降，并使源自左心室的血流量更多地流向躯体、心肌和肺。给予哌唑嗪后发生低氧血症时，不仅主动脉压及流向脑、心肌和膈肌的血流量增加，而且与药物治疗前的情况不同，心脏指数也增加。因此，在新生仔猪中，低氧血症期间关键器官的氧输送维持并未被哌唑嗪阻断，而是通过心脏指数增加来实现，而非仅仅通过血流重新分布。
