Sodium Transport and Oxygen Consumption in the Mammalian Kidney

IN the isolated frog skin, it was found by Zerahn¹ and by Leaf and Renshaw² that the amount of sodium actively transported had a fixed relationship to the net oxygen consumption (sodium/net oxygen ratio), as about 18 sodium ions were transported per molecule of oxygen consumed under a variety of experimental conditions. Net oxygen consumption was defined as the difference between the total oxygen uptake and the basal uptake, that is, the oxygen uptake when no sodium transport took place. In the mammalian kidney, active re-absorption of sodium (anions and water following passively) represents on a molar basis the overwhelming part of all tubular transport processes. On the assumption that sodium re-absorption does therefore require the bulk of the oxidative energy supplied, we have determined the sodium/net oxygen ratio in the intact kidney of the dog.