Increased O-2 consumption of the rat diaphragm by elevated NaCl concentrations

Abstract

Following observa-tions on increased O2 uptake in clinical and experimental states of water deprivation, the oxygen consumption of rat he.midiaphragms was studied in-vitro (Warburg technique) in solutions with increased osmo-lality. The addition of 10-40 mmoles NaCl to the incubating medium caused a rise in the O2 uptake by 8-32%. No change was observed when the osmolar concentration was raised by glucose, mannitol, or lithium chloride. Diaphragms from rats which had been thyroidectom-ized 2 weeks prior to the experiments showed a lower O2 uptake, but the addition of NaCl resulted in about the same increase in O2 consumption as found in preparations from nonoperated or control-operated animals. The effect of added NaCl on the O2 uptake was markedly reduced when ouabain (10-5 [image] ) was present in the incubating medium. It is concluded that the increased 02 consumption reflects the additional energy requirements when the cellular sodium pump has to work against raised extracellular sodium concentrations.