Effects of steroids and cyclosporin A on compensatory renal growth and plasma electrolytes in rats.

The uninephrectomized rat presents a reasonable model for the kidney transplant patient and allows for the study of the actions of steroids and immunosuppressive agents under conditions of stimulated renal growth. Following 2 weeks of treatment, neither cyclosporin A nor corticosterone affected the growth of the remaining kidney. The degree of compensatory renal hypertrophy was inhibited to some extent by the administration of prednisone. Renal concentrations of protein and nucleic acids were relatively uninfluenced by these agents, compared with uninephrectomized control values. Testosterone caused little change in renal mass but did incur significant reductions in protein and RNA levels, suggestive of a protein catabolic action. In examining the plasma levels of electrolytes normally handled by the kidney, testosterone also gave rise to losses of plasma potassium and calcium, whereas cyclosporin A administration led to a more pronounced lowering of calcium and magnesium levels. More detailed studies of the actions of these drugs on renal growth and function are desirable in view of their clinical potential and usage.