The effect of temperature on the basal metabolism of cardiac muscle.

Using independent methods, measurements were made of the rate of oxygen consumption of quiescent rat ventricular tissue slices and of K+-arrested rabbit hearts at different temperatures. Experiments were designed such that the effect of temperature could be separated from the effect of time. The rate of oxygen consumption of both cardiac muscle preparations declined with time following cardiectomy. Likewise the rate of resting oxygen consumption of both preparations was relatively insensitive to temperature: Q10 = 1.3. By contrast, the rate of oxygen consumption of rat liver slices showed a Q10 of 2.6. The low Q10 values of the cardiac preparations do not appear to be due to an inadequate supply of oxygen. The results are in close agreement with those of myothermic studies.