Effect of acetylcholine and ischaemia/reperfusion injury on the heart of rats with STZ-induced experimental diabetes

OBJECTIVES: To investigate the effect of acetylcholine (ACh) and ischaemia/reperfusion injury on functional changes and dysrhythmias of the isolated diabetic rat heart. METHODS AND RESULTS: On retrogradely perfused hearts isolated from 10-week-old diabetic rats (streptozotocin 30mg/kg b.w. for three consecutive days i.p.), two types of experiments were done: /1/ The effect of acetylcholine (ACh; 3x10(-7) mol/l) was evaluated both during and after infusion, and /2/ the influence of the ischaemia/reperfusion injury (I/R) was studied. At the end of both experiments the hearts were electrically stimulated to evoke sustained ventricular fibrillation (VF). An increase of coronary arterial pressure, bradycardia and decreased total number of severe dysrhythmias of both types, spontaneous and evoked ones, were recorded in the diabetic hearts. ACh increased the force of contraction (LVP) and induced vasoconstriction, which persisted in the diabetic hearts even after removal of ACh from the perfusion solution. CONCLUSIONS: The isolated diabetic rat heart was more resistant against severe dysrhythmias. After washing out the ACh, the vasoconstriction of coronary arteries still lasted, along with increased inotropic effect on the left ventricle.