Effect of stress adaptation on cyclic nucleotide content in myocardial tissue during acute ischemia/reperfusion.

We studied the effect of adaptation to chronic immobilization stress on the contents of cyclic adenosine monophosphate and cyclic guanosine monophosphate in myocardial tissue during coronary occlusion and reperfusion. The contents of cyclic adenosine monophosphate and cyclic guanosine monophosphate in the ischemic area and nonischemic myocardium of unadapted rats increased during coronary artery ligation for 10 min. Reperfusion for 10 min was followed by an increase in the content of cyclic adenosine monophosphate. During coronary occlusion, the content of cyclic adenosine monophosphate in the myocardium of stress-adapted rats increased less significantly than in control animals. No significant differences were found in the content of cyclic guanosine monophosphate in control and adapted rats. Our results suggest that poor response of the myocardial cyclic nucleotide system to ischemia/reperfusion in adapted animals is associated with the antiarrhythmic and cardioprotective effect of adaptation.