Erythrocyte sodium metabolism and renal sodium excretion in spontaneously hypertensive rats (SHR) and related normotensive rats (WKY).

SHR being in osmotic diuresis responded to an intravenous saline load with greater sodium excretion than WKY. Volume expansion and sodium loading did not affect the erythrocyte sodium content. Both in the non-infused and in the infused sodium-loaded state SHR had a greater Na-Li-exchange rate than WKY. In the SHR the net-22Na-gain(Ery) was not influenced by the sodium loading procedure. In WKY infusion and sodium loading induced a faster erythrocyte 22Na-uptake and a lower ouabain effect on the net-22Na-gain. The sodium metabolism differences in SHR and WKY could be due to cell membrane differences or different hormonal responses to volume and sodium loading and may be important for the sodium excretion pattern in SHR and WKY.