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Effects of carbamylcholine on the ventricular fibrillation threshold and its relation to the levels of cAMP and cGMP in rat ischemic ventricle

Wu Ying, Chen Gengxin, Hsu Hsuechang

Department of Physiology, Zhejiang Medical University. Hangzhou, Zhejiang, China

Abstract

The purpose of this study is to investigate the effects of cholinomimetic agent, carbamylcholine, on VFT in the normal and regional ischemic isolated rat hearts in relation to the levels of cAMP and cGMP in the ischemic and non-ischemic myocardia. Carbamylcholine increased significantly the VFT in both normal and regional ischemic rat hearts, suggesting that the activity of vagal-cholinergic system might exert a protective effect against ventricular fibrillation during early AMI. It was also found that carbamylcholine elevated the levels of cGMP in the ischemic and non-ischemic myocardia but markedly lowered the level of cAMP in the ischemic myocardium, and thus the cAMP/cGMP ratio in both cases was decreased correspondingly. In contrast, adrenaline lowered VFT and elevated CAMP/cGMP ratio. The data obtained showed a high negative correlation between VFT and cAMP/cGMP ratio in the ischemic myocardium. These results suggest that the cAMP/ cGMP ratio in the ischemic myocardium might play an important role in the genesis of ventricular fibrillation. Possible mechanism involved was discussed.

Key words: Ventricular fibrillation threshold;Carbamylcholine;Adrenaline;Cyclic adenosine 3' S'-monophosphate;Cyclic guanosine 3' 5'-monophosphate

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Citing This Article：

Wu Ying, Chen Gengxin, Hsu Hsuechang. Effects of carbamylcholine on the ventricular fibrillation threshold and its relation to the levels of cAMP and cGMP in rat ischemic ventricle. Acta Physiol Sin 1985; 37 (3): (in Chinese with English abstract).