四种麻醉药对大鼠颈动脉窦反射的影响

COMPARISON OF EFFECTS OF 4 ANESTHETICS ON CAROTID SINUS REFLEX IN RATS

Wistar大鼠25只,随机分成四组,分别经腹腔注射α-氯醛糖(75mg/kg),乌拉坦(1.4g/kg),水合氯醛(350mg/kg)或戊巴比妥钠(50mg/kg)麻醉。孤立颈动脉窦。窦内压(ISP)以5.3kPa为一梯级由0升高到37.3kPa,然后以同样梯级由37.3kPa降到0,同步记录平均动脉压(MAP)。将各级ISP与其对应的MAP值进行Logistic函数拟合,对所获得的四种麻醉药的ISP-MAP关系曲线及其有关参数进行比较。在低ISP区(0～10.6kPa),α-氯醛糖组的反射值明显高于其余三组;在高ISP区(26.6～37.3kPa),四组之间无差异。α—氯醛糖组峰斜率最大,乌拉坦组的闽值和P_3大于其余三组。表明α-氯醛糖可能有易化大鼠窦反射的作用,其余三种麻醉药对窦反射有抑制作用,其中乌拉坦的抑制效应最大。

In order to determine the effects of different anesthetics on the performance of the arterial baroreflex, characteristics of the carotid reflex were analyzed in 25 Wistar rats under anesthesia with a-chloralose (75mg/kg), urethane (1.4g/kg), chloral hydrate (350mg/kg) and pentobarbital sodium (50mg/kg). The left isolated carotid sinus and left femoral artery were cannulated respectively. Intrasinus pressure (ISP) and mean arterial pressure (MAP) were simultaneously recorded. For each rat and anesthetic, MAP was measured as ISP was changed at 5.3kPa steps between 0 and 37.3kPa. A logistic function curve was fitted to the ISP-MAP relationship. The parameters of these curves were then analyzed to delineate the specific effects of 4 anesthetics on the relationship. The main findings were that the MAP under α-chloralose anesthesia at low ISP area was significantly higher than those obtained with other anesthetics, while no significant difference among four anesthetic groups at high ISP area was found. The peak slope of a-chloralose group was the largest, while no significant difference was observed among the other three groups. The threshold and P3(the ISP at which the slope of the curve is steepest) of urethane group were larger than those of the other groups. It is concluded that a-chloralose may sensitize carotid sinus baroreflex, while the three others inhibit it, of which, urethane was the most strong one.