静脉注射不同剂量肾上腺素对大鼠血压的影响

目的不同剂量的肾上腺素可激动不同的肾上腺素能受体,然而,尚无文献报道静脉注射不同剂量的肾上腺素对血压有何不同的影响。文中观察静脉注射不同剂量肾上腺素对大鼠血压的影响,并探讨其可能的机制。方法选择成年雄性SD大鼠40只,体重350～400 g,随机均分为5组(n=8)。其4组(E1-4组)分别经股静脉注射肾上腺素0.125μg/kg、0.25μg/kg、0.5μg/kg和1μg/kg,另一组(S组)经股静脉注射等容等渗盐水。记录肾上腺素或等渗盐水注射前(T0)基础值和注射后5、10、15、30 s及1、2、3、4、5 min(T1-9)时的平均动脉压(mean arterial pressure,MAP)和心率(heart rate,HR)。结果各组MAP基础值(T0)无明显差异。与T0时MAP相比,E1组各时间点无明显改变;E2组T2-5时下降(P<0.05),T6时恢复至基础值水平;E3组T1时上升,T3-4下降(P<0.05),T5时恢复至基础值水平;E4组T1-7时上升(P<0.05),T8时恢复至基础值水平。HR在E4组T1-6时增加,余各组各时间点未见明显改变。结论小剂量肾上腺素静脉注射引起大鼠血压下降;中剂量引起血压先升后降的双相变化;大剂量引起血压升高。

Effects of different doses of epinephrine intravenous injection on blood pressure in rats

Objective Different doses of epinephrine activate different adrenergic receptors.However,there is no report concerning the effects of different doses of intravenously injected epinephrine on blood pressure.This study was to observe the effects of different doses of intravenously injected epinephrine on blood pressure in rats and explore the possible mechanism.Methods Forty Sprague-Dawley male rats,weighing 350-400 g,were equally randomized into 5 groups: E1,E2,E3,E4 and S.The E1-4 groups were intravenously injected with epinephrine at 0.125,0.25,0.5 and 1 μg/kg,respectively,while the S group with equal volume of saline.The mean arterial pressure(MAP) and heart rate(HR) were recorded before(baseline,T0) and at 5 s,10 s,15 s,30 s,1 min,2 min,3 min,4 min,and 5 min(T1-9) after the intravenous injection.Results MAP showed no significant differences at T0 among all the groups,nor at all time points in the E1 group as compared with T0.MAP decreased at T2-5 in the E2 and at T3 and T4 in the E3 group,but increased at T1-7 in the E4 group(P<0.05).HR increased at T1-6 in the E4 group,exhibited no significant changes in the other groups at all time points.Conclusion Intravenous injection of epinephrine decreases blood pressure(BP) in rats at a low dose,induces a biphasic BP change of first-rise-and-then-fall at a median dose,and elevates BP at a high dose.