This study was designed to determine the effects of the cardiac depressant, quinidine, on the metabolism of glucose and free fatty acids, major substrates for energy production by heart muscle, as a possible explanation for its pharmacological action on the heart.
Dog heart tissue slices, 150 mg, were incubated in Krebs Ringer phosphate and bicarbonate buffers containing 10 mmole glucose-U-C14 or 0.0125 mmole palmitate-U-C14 with 1 X 10-4M, 5 X 10-4M, and 1 X 10-3M quinidine sulfate. Oxygen consumption, glucose uptake, net lactate formation, net glycogen change, and the incorporation of glucose-U-C14 and palmitate-U-C14 into C14O2 were measured directly.
Oxygen