模拟失重大鼠左心室乳头肌收缩性能及钙反应性的变化

THE CHANGES OF THE CONTRACTLLITY AND RESPONSIVENESS TO CALCIUM OF LEFT VENTRICULAR PAPILLARY MUSCLES IN RATS DURING SIMULATED WEIGHTLESSNESS

采用改进的Ｍｏｒｅｙ－Ｈｏｌｔｏｎ尾部悬吊大鼠模型模拟失重状态和用离体乳头肌灌流技术，观察模拟失重大鼠左心室乳头肌收缩性能与钙反应性的变化过程。结果表明，模拟失重１周，收缩性能呈增高趋势；２周时，收缩性能有降低趋势；４周时，收缩性能明显降低，主要表现为等长张力降低２９．２％，达到张力峰值的时间延长１０．４％，舒张时间则呈降低趋势。另外，模拟失重４周大鼠乳头肌对Ｃａ２＋的反应性均较相应的对照组明显降低。这些变化提示，４周模拟失重可能引起心肌肌原纤维含量减少和肌浆网Ｃａ２＋运转功能降低。

The modified Morey-Holton's tail-suspended rat model was used to simulate the effect ofmicrogravity on cardiovascular system. Using the technique of isolated papillary muscleperfusion,the isometric contraction tension and its time parameter were observed.The resultswere as follows:The contractility of papillary muscles from rats with tail suspended for 1 and 2weeks didn't show significant changes as compared with their control rats.However,the tail-sus-pension for 4 weeks caused a 29.2% decrease in the peak isometric developed tension and signifi-cant prolongation of time to peak isometric tension and a shortening trend of time to half relaxa-tion.In addition,the response curves to increasing extracellular Ca2+ concentration was de- pressed in papillary muscles of 4-week tail-suspended rats.The results suggest that simulatedweightlessness for 4 weeks may cause decrease in the content of myofibrils and depression in thefunction of sarcoplasmic reticulum.