Monma Y, Okuoka Y, Kameda H, Ichihara K, Abiko Y, Tanabe T
Nihon Yakurigaku Zasshi. 1980 May;76(4):239-54.
Effects of labetalol on the cardiovascular system were studied in dogs, guinea pigs, rats, rabbits, and bullfrogs. In dogs anesthetized with pentobarbital, labetalol decreased heart rate, arterial blood pressure, and myocardial contractile force, and inhibited carotid sinus reflex, without affecting pO2 and pH of circulating blood, urine volume, and urinary excretion of sodium and potassium. Alpha- and beta-adrenergic blocking action of labetalol was demonstrated in dog hearts, arterial preparations of guinea pigs and rats, isolated rabbit hearts, and bullfrog hind limb and rabbit ear preparations. In bullfrog hind limb and rabbit ear preparations, labetalol dilated blood vessels in concentrations larger than those which produced alpha- and beta-adrenergic blockade. The dilatation of blood vessels was observed only when labetalol was added to the perfusate, whereas alpha- and beta-adrenergic blockade continued even after removal of labetalol from the perfusate. It is concluded that labetalol blocks alpha- and beta-adrenergic receptors in the heart and blood vessels of the species used herein, and that this compound inhibits carotid sinus reflex in dogs. In addition, the dilatation of the blood vessels of the bullfrog hind limb and rabbit ear as evoked by labetalol probably involves a mechanism different from that of adrenergic blockade.
在犬、豚鼠、大鼠、兔和牛蛙中研究了拉贝洛尔对心血管系统的作用。在用戊巴比妥麻醉的犬中，拉贝洛尔降低心率、动脉血压和心肌收缩力，并抑制颈动脉窦反射，而不影响循环血液的pO2和pH、尿量以及钠和钾的尿排泄。拉贝洛尔的α和β肾上腺素能阻断作用在犬心脏、豚鼠和大鼠的动脉制备物、离体兔心脏以及牛蛙后肢和兔耳制备物中得到证实。在牛蛙后肢和兔耳制备物中，拉贝洛尔在高于产生α和β肾上腺素能阻断的浓度下使血管扩张。仅当将拉贝洛尔加入灌流液中时才观察到血管扩张，而即使从灌流液中去除拉贝洛尔后，α和β肾上腺素能阻断仍持续存在。得出的结论是，拉贝洛尔阻断本文所用物种心脏和血管中的α和β肾上腺素能受体，并且该化合物抑制犬的颈动脉窦反射。此外，拉贝洛尔引起的牛蛙后肢和兔耳血管扩张可能涉及与肾上腺素能阻断不同的机制。
