Metabolic control of intracellular ion concentrations in the frog skin epithelium

The effects of the metabolic inhibitors 2-deoxy-d-glucose and monofluoroacetate on intracellular ion concentrations and Na transport rate were investigated in the isolated frog skin epithelium of Rana pipiens. Ion concentrations were determined in thin freeze-dried cryosections using energy-dispersive X-ray microanalysis. Metabolic inhibition was compared to direct inhibition of the Na pump by ouabain. At similar rates of transepithelial Na transport, inhibition of the Na pump always resulted in much more pronounced Na concentration increase than metabolic inhibition. This result suggests that the apical Na influx is under effective metabolic control. Downregulation of the Na influx during impaired cellular energy metabolism may be a means by which transporting epithelial cells avoid potentially damaging derangements of the intracellular ion composition.