Effect of temperature and medium K on Na and K fluxes in separated renal tubules

Abstract

The effects of temperature and medium K concentration on the concentrations and fluxes of Na and K in suspensions of separated rabbit renal tubules have been investigated. The major findings are as follows: Decrease in the temperature of the bathing medium did not result in diminution of the concentration gradients for Na and K between tissue and medium or in swelling of the tissue. However, a large decrease in Na and K flux was observed, suggesting similar temperature coefficients for both active transport and passive permeability over the range of temperatures examined (15-37 C). Removal of K from the bathing solution reduced active Na efflux. At least 2 tissue K compartments were present, probably representing the heterogeneity of the tubule population in the suspension rather than multiple compartments within individual cells. At least 2 tissue Na compartments were also observed, but no consistent relationship was found between the size or exchange rates of the individual Na and K compartments.