Effect of Metabolic Inhibitors and Ischaemia on Contractile Force and Magnesium Efflux in the Isolated Perfused Rat Heart
This study investigates the effects of ischaemia using reduced flow rate and metabolic inhibition by rotenone, KCN, oligomycin and DNP on contractile force and net Mg2+ efflux from the isolated perfused rat-heart. There was a significant (Student’s t-test; P < 0.01) decrease in force of contraction and coronary pressure during 10 min of ischaemic conditions and this was accompanied by a significant (P < 0.001) increase in Mg2+ efflux. Perfusion of the heart for 10 min with Mg2+-free KH containing metabolic inhibitors either 10-5M rotenone, 10-7M KCN. or 10-7 Oligomycin B resulted in a decrease in contractile force and a small but not significant (P > 0.01)increase in net Mg2+ efflux. In contrast, perfusion with DNP, an oxidative phosphorylation uncoupler, resulted in a significant decrease in contractile force accompanied by a highly significant (increase in Mg2+ efflux. The results indicate that both ischaemia and loss of the mitochondrial proton gradient are associated with Mg2+ efflux, and a concomitant decrease in contractile force in the isolated heart.
KeywordsContractile Force Metabolic Inhibitor Effluent Sample Coronary Pressure Perfusion Flow Rate
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