THE RELATIONSHIP OF SODIUM, POTASSIUM, AND DEOXYCORTICOSTERONE IN NEUROSPORA CRASSA

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Abstract
The effects of 11-deoxycorticosterone (DOC), azide, and exogenous K on Na uptake and intracellular K levels in N. crassa have been examined. Germinated conidia suspended in buffered saline solutions achieve an Intracellular concentration of Na approximating that of the suspending medium. The uptake of Na is not accompanied by a corresponding decrease in intracellular K, and at almost all concentrations of Na employed no marked change in intracellular K was observed. DOC appeared to augment the rate of Na influx somewhat, but had no pronounced effect on the final level of equilibrium; the presence of DOC caused a modest efflux of K. Azide inhibited influx or efflux of Na; but had no appreciable effect on the levels of Na already present in the cells; azide also had little effect on intracellular levels of K. When K was added to the cell suspension it was taken up and accumulated against an apparent concentration gradient. In the presence of exogenous K the uptake of Na was inhibited and the intracellular content of Na was decreased markedly. The exclusion of Na accompanying the accumulation of K was prevented by the presence of DOC. The implications of these observations are discussed with respect to problems of ion accumulation and exclusion, and to the nature of the hormonal action of DOC.