Oxygen consumptions and potassium contents of slices of rat renal cortex

An oxygen electrode respirometer for determining the oxygen consumption of slices of mammalian renal cortex is described and assessed. Though rat renal cortical slices incubated in potassium-free medium for one hour lost 102 +/- 14 mmol of potassium/kg dry weight, there was only a small, nonsignificant fall in oxygen consumption. In contrast the oxygen consumption of slices incubated in potassium-free medium with 10 mmol.1-1 ouabain was markedly reduced (by 32 +/- 6%), while such slices lost 180 +/- 15 mmol of potassium/kg dry weight. These disproportionate effects on potassium loss and inhibition of oxygen consumption suggest that in renal cortical slices the loss of potassium in low potassium medium is not primarily due to inhibition of the conventional sodium pump.