Effect of dietary K+ and 75% nephrectomy on the morphology of principal cells in CCDs.

This investigation was carried out to determine the effect of potassium on the amplification of the basolateral membrane of principal cells in cortical collecting ducts (CCDs), which normally occurs after a large reduction of renal mass. Rats that underwent a 75% reduction of renal mass and were fed a diet deficient in potassium for 10 days after surgery had a lower concentration of potassium in the blood and excreted less potassium in the urine than either corresponding sham-operated (SO) rats or 75% nephrectomized (NPX) rats fed a normal-potassium diet. In the NPX rats fed the diet deficient in potassium, there was a marked inhibitory effect on the amplification of the basolateral membrane, which normally occurs in principal cells of CCDs after renal mass has been greatly reduced. In fact the surface density of the basolateral membrane, as well as the size of the principal cells in the animals fed the diet deficient in potassium were the same as those of principal cells in the SO rats fed the normal-potassium diet. Thus the present data show that the increase in cell size and the amplification of the basolateral membrane that occurs in principal cells after a 75% reduction of renal mass is inhibited by factors associated with potassium depletion.