外源性钙对放烧复合伤早期心肌线粒体呼吸功能的影响

Effects of exogenous calcium on myocardial mitochondrial respiratory function at the early stage after combined radiation-burn injury in rats *

目的：了解外源性钙离子对放烧复合伤心肌线粒呼吸功能的影响。方法：Ｗｉｓｔａｒ大鼠分为正常对照组，６Ｇｙ照射复合３０％ＴＢＳＡⅢ度烧伤组、放烧复合伤预防用药组和放烧复合伤治疗用药组。于伤后１、１２、２４和４８ｈ测定不同浓度钙对各组线粒体呼吸功能的影响。结果：低浓度外源性钙（１０μｍｏｌ／Ｌ）对正常对照组心肌线粒体呼吸有刺激作用，但对放烧复合伤组、放烧复合伤预防用药组和治疗用药组线粒体呼吸无显著刺激作用；高浓度外源性钙（５０μｍｏｌ／Ｌ）对正常组、放烧复合伤预防用药组和治疗用药组心肌线粒体呼吸功能有显著抑制作用，但使复合伤组心肌线粒体呼吸完全脱偶联。１８７．５μｍｏｌ／Ｌ维拉帕米可显著减轻５０μｍｏｌ／Ｌ钙离子对呼吸的抑制。结论：放烧复合伤心肌线粒体对外源性钙的耐受性降低，维拉帕米预防或治疗用药均能提高复合伤后线粒体对外源性钙的耐受性。

Objective: To study the effects of exogenous calcium on myocardial mitochondrial respiratory function at the early stage after combined radiation-burn injury. Methods: Adult male Wistar rats were randomized into four groups: 1) Normal control group (NCG); 2) Combined radiation-burn injury group (CRBIG); 3) Prevention group (PG); 4) treatment group (TG). The effects of exogenous calcium of various concentration on myocardial mitochondrial respiratory function were determined at the 1st, 12th, 24th and 48th hour after the injury in all the groups. Results: Exogenous calcium of low concentration (10 μmol/L) exerted significant stimulative effects on myocardial mitochondrial respiratory function of the rats in NCG but did not do the same on that in CRBIG, PG and TG. However, exogenous calcium of high concentration (50 μmol/L ) inhibited the myocardial mitochondrial respiratory function of rats in CG, PG and TG and completely uncoupled the oxidative phosphorylation of myocardial mitochondria in CRBIG, which could be markedly released with 187.5 μmol/L Verapamil. Conclusion: The reduced myocardial mitochondrial tolerance in the rats inflicted with combined radiation-burn injury can be enhanced by the prophylactic or therapeutic administration of verapamil.