Yang S T, Koong C W, Chen H I
Department of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan, ROC.
Chin J Physiol. 1997 Sep 30;40(3):137-42.
Endothelium-derived prostaglandins appear to play an important role in myogenic contraction of the cerebral arteries in response to increased transmural pressure. The goal of this study was to determine whether prostaglandins contribute to the autoregulatory response of cerebral blood flow (CBF) during acute hypertension in normotensive and chronically hypertensive animals. In 4-5 months old Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) anesthetized with pentobarbital sodium (45 mg/kg, i.p.), regional CBF of the right parietal cortex was monitored by laser-Doppler flowmetry. Acute hypertension was induced by intravenous infusion of phenylephrine and the elevated arterial pressure was maintained for 50 seconds for the measurement of CBF. In the control group of WKY rats, CBF increased by 5.6% per 10-mmHg increase in arterial pressure. Changes in CBF were similar between the initial state (0-10 seconds) and the steady state (30-40 seconds) of acute hypertension. In WKY rats pretreated with indomethacin (10 mg/kg, i.v.), increases in CBF in the initial state were slightly but significantly greater than that in the steady state. Indomethacin also tended to enhance the increases in CBF in both the initial state and the steady state; however, the effect was not significant. In the control group and indomethacin-pretreated group of SHR, acute hypertension produced similar increases in CBF. In both groups, no significant difference between changes in CBF in the initial state and the steady state was observed. Thus our findings suggest that 1) in normotensive animals, the early autoregulatory response of CBF during acute hypertension is partially mediated by prostaglandins and 2) the role of prostaglandins in the regulation of CBF during acute hypertension is altered in chronically hypertensive animals.
内皮衍生的前列腺素似乎在脑动脉对跨壁压升高的肌源性收缩中起重要作用。本研究的目的是确定在正常血压和慢性高血压动物急性高血压期间，前列腺素是否对脑血流量（CBF）的自动调节反应有贡献。在用戊巴比妥钠（45mg/kg，腹腔注射）麻醉的4-5月龄Wistar-Kyoto（WKY）大鼠和自发性高血压大鼠（SHR）中，通过激光多普勒血流仪监测右顶叶皮质的局部CBF。通过静脉输注去氧肾上腺素诱导急性高血压，并将升高的动脉压维持50秒以测量CBF。在WKY大鼠的对照组中，动脉压每升高10mmHg，CBF增加5.6%。急性高血压初始状态（0-10秒）和稳态（30-40秒）之间CBF的变化相似。在用吲哚美辛（10mg/kg，静脉注射）预处理的WKY大鼠中，初始状态下CBF的增加略高于但显著高于稳态。吲哚美辛也倾向于增强初始状态和稳态下CBF的增加；然而，效果不显著。在SHR的对照组和吲哚美辛预处理组中，急性高血压使CBF产生相似的增加。在两组中，未观察到初始状态和稳态下CBF变化之间的显著差异。因此，我们的研究结果表明：1）在正常血压动物中，急性高血压期间CBF的早期自动调节反应部分由前列腺素介导；2）在慢性高血压动物中，前列腺素在急性高血压期间CBF调节中的作用发生了改变。
