Effect of hypo- and hypertonic saline and raffinose on cell content of Na, Cl and K in respiring rat kidney cortex at 37 degree.

Changes in cell Na, K and Cl content (per kg dry weight) and concentration (per kg intracellular water) were measured in respiring rat renal cortical slices incubated for 60 min at 37 degree in hypo- and hypertonic saline with and without the addition of a non-electrolyte (raffinose). Both hypertonic saline and raffinose increased cellular concentration of Na, Cl and K, the former by producing minimal cell shrinkage and major entry of Na and Cl into the cell, the latter entirely by cell shrinkage leading also to a loss of Na content but not of K. In hypotonic saline both content and concentration of Na and Cl did not change significantly, whereas that for K dropped markedly. Addition of ouabain (1 mmol/1) produced a significant gain of cell Na and loss of K on a one to one basis but did not alter the effect of raffinose. It is concluded that sustained changes in cell ion concentrations and content in response to pericellular osmolality are produced and that these are directed towards equilibrating cellular activity of water to that of the surrounding medium.