心得安对模拟甲状腺功能亢进兔心功能的作用

Effect of Propanolol on Rabbit Heart Function Simulating Hyperthyroidism

本文测定肌注左旋甲状腺素(L-T_4)及 L-T_4加心得安引致甲状腺功能亢进状态动物与注射等量生理盐水作为正常对照组的动物的心功能。结果:L-T_4注射组及 L-T_4加心得安注射组动物的心率、心脏收缩功能(LVSP、+dp/dt-max、Vpm)及舒张功能指标(-dp/dt-max、-dp/dt/-p)均显著高于对照组(P<0.05～0.001),但 L-T_4注射组与 L-T_4加心得安注射组动物比较无显著差异(P>0.05)。L-T_4注射组动物血浆总 T_3、T_4水平与+dp/dt-max 呈显性正相关。本实验结果提示:甲状腺激素作用于心脏可产生正性变力和变时作用,心得安不能抑制此作用,表明其作用环节可能是不依赖于心肌β受体的直接作用。

The maximum rate of intraventricular pressure rise (+dp/dt-max),physiologicalmaximal shortening or relaxing velocity (+dp/dt/-p) and heart rate were measuredin three groups of rabbits.Group 1 was experimentally produced hyperthyroidismicby intramusclar injection of L-T4 200g/kw on the first day and 100g/kg/day fromthe 2nd to 22th days,then 50g/kg/day up to 6 weeks.Group 2 was injected L-T4together with propanolol 1.0mg/kg/day.Group 3 was the control in which and 0.9%NaCl solution was intramuscularly injected.The results,indicated that the plasmaT3 concentration in both group 1 and 2 were significantly higher then in group 3(P<0.01).So were the HR,+dp/dt-max,+dp/dt/-p and LVSP (P<0.05-0.001).Butall these changes were not significantly different between groups 1 and 2(P>0.05).Furthermore it was found that in group 1 the plasma T3 and T4 levels were posi-tively correlated with +dp/dt-max(T3 r=0.8040 P<0.005:T4 r=0.6816 P<0.05).It wasconcluded that the thyroid hormone had positive inotropic effect in the heart bydirect action other than that of myocardium β-adrenoreceptor.