幼鼠肺炎合并心衰的分子机制研究

STUDIES ON MOLECUAR MEEHANISM OF HEART FAILURE SECONDARY TO PNEUMONIA IN RATS

目的:从细胞和分子水平揭示婴幼儿肺炎合并心衰的机制。方法:健康清洁级50日龄Wistar大鼠。经气管注射金黄色葡萄球菌菌液,建立肺炎动物模型;开胸获取心脏,进行双心室灌流,测定心肌酶谱和心功能指标;酶解分离出单个右室心肌细胞后,以Fura-2/AM负载细胞并对静息和收缩状态时细胞内[Ca^(2+)]i进行荧光测定;采用全细胞式膜片钳技术记录右室心肌细胞L型钙电流;采用高效液相色谱仪测定心肌组织腺苷酸含量。均采用气管内注射等量生理盐水的同龄Wistar大鼠作为对照。结果:1、肺炎组动物心肌酶谱显著增高。2、肺炎组和对照组的左、右心室功能均随前负荷升高而增强;在同一负荷下,右心室功能均低于对照组。3、静息状态下肺炎组右室心肌细胞内[Ca^(2+)]i随病程显著增高;收缩时CO^(2+)含量增加比率显著低于对照组。4、接种后24h的肺炎组L型钙通道电流峰值无显著变化;120h时显著高于对照组。5、接种后120h,心肌组织腺苷酸含量显著低于对照组。结论:采用气管内接种的方法所建立肺炎动物模型是有效的;肺炎可以合并心衰.尤其是右心衰竭为主;重症肺炎时心肌细胞出现能量代谢障碍;静息期心肌细胞内[Ca^(2+)]i增高.而收缩状态下Ca^(2+)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。心肌细胞跨膜钙内流增大。可能是病变发展的重要机制。

Objective: To probe the mechanism of heart failure incurred with infantile pneumonia both at the cellular level and at molecular level.Materials and methods: Bacterial solution was injected into tracheas of 50-day-old Wistar rats to obtain the pneumonic animal model.After chest opening, the heart was acquired and perfused with biventricular methods.Cardiac enzymes spectrum and cardiac function were further measured.After isolation with certain enzymes and loaded with Fura— 2/AM, [Ca^(2+)]i of right ventricular myocyte was measured.The whole-cell clamp was used to record the L-type calcium current.And ATP contents were of building control.Results: 1.Cardiac enzymes spectrum of pneumonia rats was measured to significantly high.2.For both pneumonic and control rats, cardiac function positively responded to forward load.The function of right ventricular of pneumonic rata was significantly lower than that of controls at any level of forward load.3.As pneumonia developed, the [Ca^(2+)] i of right ventricular myocyte increased significantly, while it increased in significantly less amplitude when the myocyte contracted.4.24h after bacterial injection, the peak current of L-type calcium ion kept almost unchanged, but significantly increased 120h after injection.5.120h after bacterial injection, ATP contents significantly decreased.Condnsion: 1.Bacterial injection via trachea proved to be an effective way to build pneumonic animal model.2.It is proved that heart failure, especial right ventricular dysfunction followed serious pneumonia.Dysfunction of energetic metabolism also occurred.3.In the rest period, right ventricular myocyte had a higher[Ca^(2+)]i, while it has less potential to increase [Ca^(2+)] when the myocyte contracted.This could be an important mechanism of heart failure after pneumonia.And in advanced period of heart failure, the increased L-type calium ion may also be an import mechanism of its development.