婴幼儿肺炎并心力衰竭发病机制的实验研究

目的观察肺炎时心肌细胞跨膜L型钙电流与细胞内Ca2 含量的动态改变,探讨肺炎并心衰的可能发生机制。方法取50日龄Wistar大鼠,经气管注入金黄色葡萄球菌,建立肺炎模型。急性酶解分离出右室心肌细胞。1.以Fluo-3-AM标记细胞内Ca2 ,分为生理盐水对照组、接种后24、72h肺炎组,应用黏附细胞仪研究肺炎对静息和收缩状态下细胞内Ca2 含量的影响。2.另分接种后24、120h肺炎组及对照组,记录各组细胞膜L型钙电流。结果1.肺炎组24h静息状态心肌细胞内Ca2 含量无显著改变,而72h肺炎组显著增高(P<0.001);加入KCl后2.5min,24h肺炎组心肌细胞内Ca2 含量增加比率显著低于对照组(P<0.05),5.0、7.5、10.0min,两者无显著性差异。而72h肺炎组增加比率在前10min内均低于对照组。2.肺炎组与对照组24h电流峰值无差异,120h时则显著高于对照(P<0.001)。结论重症肺炎时右室心肌细胞发生钙代谢障碍,静息期心肌细胞内Ca2 浓度增高,而收缩状态下Ca2 含量增加比率下降,可能是心肌细胞舒张、收缩功能障碍的重要机制;心衰后期,心肌细胞钙内流增大,可能是病变发展的重要机制。

Experimental Study on Mechanism of Heart Failure during Acute Infantile Pneumonia

Objective To have a better understanding of the possible mechanism of heart failure secondary to acute pneumonia by recording cardiomyocyte L-type Ca 2 current and intracellular Ca 2 content change.Methods Animal models of acute pneumonia were established by inoculating via trachea staphylococci aureus into 50 day old Wistar rats. Right ventricular myocytes were enzymatically isolated. 1. Animals were randomly divided into 3 groups, 10 in each group, namely 24-hour pneumonic group,72-hour pneumonic group and physiological saline control. And intracellular calcium ions were marked by fluo-3-AM.Twenty four or 72 hours after inoculation, fluorescence intensities of isolated myocytes were compared with those of the controls under both quiescent and contracting conditions by applying adherent cell analysis sorting cytometer 570 ( ACAS 570).2.Thirty two animals were averagely divided into 4 groups, namely 24 hours pneumonic group, 120 hour pneumonic group and their respective controls. Transmembrane Ca 2 current through L-type channels was recorded by the whole-cell clamp technique.Results 1. 24 hours after inoculation, little change occurred to the content of intracellular Ca 2 of quiescent myocytes and 2.5 minutes of exposure duration extended to 5 or 7.5 or 10 minutes, and no significant difference could still be found.Seventy two hours after inoculation, intracellular calcium ions content was signi-ficantly higher under quiescent conditions ( P <0.001), but lower during the first 10 minutes of exposure to KCl( P <0.05).2. In terms of L-type Ca 2 current peak value, 24 hours pneumonic group was not significantly different from its controls, while in 120 hour pneumonic group,it was significantly greater than the controls ( P <0.001).Conclusions During acute pneumonia a disorder of intracellular calcium metabolism occurs to right ventricular myocytes. In the rest period, right ventricular myocyte had a higher (Ca 2 ), while it had less potential to increase (Ca 2 ) when the myocyte contracted. This can be an important mechanism for heart failure after pneumonia. And in the advanced period of heart failure, the increased L-type calcium ion may also be an import mechanism for its development.