低浓度毒毛旋花子苷元的强心作用及其与心肌细胞膜Na+,K+-ATP酶的关系

摘要

AIM: To evaluate the effects of strophanthidin (Str) on cardiac contractile function and sarcolemmal Na+, K+-ATPase activities in isolated guinea-pig hearts. METHODS: Isolated guinea-pig hearts were perfused through aorta in a Langendorff mode. Heart rate (HR), left ventricular pressure (LVP), and first derivatives (+dp/dtmax) of LVP were recorded by eight-channel physiological instrument. Cardiac sarcolemmal Na+, K+-ATPase activities were determined with colorimetry. RESULTS: Str 0.1 nmol/L stimulated the Na+, K+-ATPase activities (P＜0.05), but had no effect on HR, LVP, and ±dp/dtmax. Str 1 nmol/L increased +dp/dtmax (P＜0.05) and Na+, K+-ATPase activities (P＜0.01). Str 10 and 100 nmol/L significantly increased both LVP (P＜0.05) and +dp/dtmax (P＜0.05 or P＜0.01),and had no significant effects on Na+, K+-ATPase activities. However, Str 1-100 μrnol/L at first enhanced the LVP and ±dp/dtmax (P＜0.01), then reduced them resulting from irregular contraction, and effects of Str on Na+, K+-ATPase activities revealed a concentration-dependent inhibition (P＜0.01). CONCLUSION: The positive inotropic effects and irregular contraction produced by Str at higher concentrations result from the inhibition of Na+, K+-ATPase activities, and the positive inotropic effects of Str at lower concentrations are not related to the inhibition of the Na+, K+-ATPase activities.%目的:观察低浓度的毒毛旋花子苷原(Strophanthidin,Str)对离体豚鼠心脏是否有强心作用,及其与心肌细胞膜Na+,K+-ATP酶活性的关系.方法:采用Langendorff离体灌流装置经主动脉逆行灌流心脏;八道生理记录仪记录心率(HR),左室内压(LVP)及其最大变化速率(±dp/d tmax);无机磷法测定心肌细胞膜Na+,K+-ATP酶活性.结果:Str 0.1 nmol/L可兴奋Na+,K+-ATP酶活性(P＜0.05)但不影响心脏的收缩功能.Str 1 nm01/L仅能升高+dp/dtmax(P＜0.05)并兴奋Na+,K+-ATP酶活性(P＜0.01).Str 10和100 nmol/L可升高LVP和+dp/dtmax(P＜0.05或P＜0.01),对Na+,K+-ATP酶活性无明显作用.Str 1-100μml/L虽能短暂升高LVP和±dp/dtmax(P＜0.01),但随后出现不规则收缩并使LVP和±dp/d tmax降低,其对Na+,K+-ATP酶活性则表现为剂量依赖性抑制作用(P＜0.01).结论:高浓度Str的正性肌力作用是通过抑制Na+,K+-ATP酶活性实现的,而低浓度Str的强心作用似与Na+,K+-ATP酶抑制作用无关.