钙离子浓度变化对大鼠缺血心室致颤阈值的影响及其与cAMP、cGMP及ATP的关系

本文目的是观察不同钙离子浓度([Ca~(2 )])对急性局部缺血大鼠心脏室颤阈(VFT)的影响及其与心肌cAMP、cGMP和ATP含量变化的关系。结果表明,[Ca~(2 )]与缺血心脏VFT下降幅度呈正相关(r=0.7998,p<0.05);而[Ca~(2 )]与缺血心肌cAMP/cGMP比值、ATP含量则呈负相关(分别r=-0.887、r=-0.864,均p<0.05);缺血心脏VFT下降幅度与cAMP/cGMP比值亦呈显著负相关(r=-0.992,p<0.01),提示心肌细胞内游离Ca~(2 )水平可能是缺血心室易颤性(VV)的决定因素;cAMP水平或cAMP/cGMP比值则可能是通过影响Ca~(2 )内流而起作用的间接因素;而ATP贮量对缺血心脏VFT下降可能有一定保护作用。

Effect of Ca~(2 ) concentration on the ventricular fibrillation threshold and its relation to the levels of cAMP, cGMP and ATP in rat ischemic heart

The purpose of this study was to investigate the effects of different Ca~(2 ) concentrations on the ventricular fibrillation threshold(VFT) in the acute reg- ional ischemic isolated, paced rat hearts and to investigate their relations to the levels of cAMP, cGMP and ATP in the myocardium. It was demonstrated that a positive correlation was observed between [Ca~(2 )] and the percentage of VFT lowered in the ischemic hearts (r=0.7998, P<0.05). However, there were negative correlations between [Ca~(2 )] and cAMP/cGMP ratio and between [Ca~(2 )] and ATP contents in the ischemic myocardia (r=-0.887 and r=-0.864, respectively, P<0.05 either). It was also found that a significant negative correlation existed between the percentage of VFT lowered and cAMP/cGMP ratio in the ischemic hearts (r=-0.992, P<0.01). The results obtained in this study indicate that intracellular free Ca~(2 ) level may be a deteminant of ventricular vulnerability to fibrillation in the ischemie hearts; the level of cAMP or cAMP/cGMP ratio may be an indirect factor to affect ventricular vulnerability by modulating Ca~(2 ) influx through the cell membrane. The ATP content stored in the ischemic myocardium appears to play a beneficial and protective role in the ventrieular vulnerability to fibrillation.