Effect of methylprednisolone on renal function and the zonal distribution of blood flow in the rat.

The effect of acute and chronic administration of methylprednisolone on renal function was studied in rats with clearance and micropuncture techniques. Although acute administration did not influence renal function, chronic administration for 4 days caused a marked increase in glomerular filtration rate and PAH clearance. The rise in the reabsurption of sodium under these conditions was associated with a disproportionate increase in filtration rate and renal blood flow in deep portions of the cortex. There was no evidence of altered fractional sodium reabsorption in the proximal segment of surface nephrons by micropuncture analysis or in the ascending limb by clearance studies during a water or a solute diuresis.