Micropuncture study of renal transtubular concentration gradients of sodium and potassium in adrenalectomized rats

Summary Samples of proximal and distal tubular fluid were collected from control rats and from adrenalectomized animals maintained on 0.9% NaCl solution. Plasma and tubular fluid were analyzed for Na²² after adequate isotope equilibration and for Na and K by microflamephotometry. Similar analyses were performed in stationary microperfusion experiments in which the magnitude of the limiting concentration gradients for Na and K was estimated. Transtubular electrical potential differences were measured by means of glass-microelectrodes. A comparison of proximal tubular concentration gradients showed no significant differences between the control and the adrenalectomized rats for either Na or K. In contrast, the ability of the distal tubular epithelium to develop concentration gradients for Na and K was significantly reduced by adrenalectomy. This functional impairment could be reversed by the administration of d-aldosterone. No changes in proximal and distal transtubular electrical potential differences were observed in the various experimental conditions.With 5 Figures in the TextThis work was supported by grants from the National Institutes of Health, the National Science Foundation, the American Heart Association, the Life Insurance Medical Fund and the Deutsche Forschungsgemeinschaft.Part of this material was presented in abstract form [Pflügers Arch. ges. Physiol. 279, R 26 (1964)].Supported by Deutsche Forschungsgemeinschaft.Supported by Public Health Service Research Career Program Award (5-k6-AM-18).New York Health Research Council Career Scientist.