Increased Diuretic Response to Furosemide in Rats with Glycerol-Induced Acute Renal Failure

To clarify the diuretic response to furosemide in a diseased state, the urinary excretion of furosemide, water, and electrolytes was examined after a single intravenous injection of furosemide in control rats and rats with mild acute renal failure (ARF) induced by glycerol. The urinary recovery of furosemide was similar in the control and ARF rats. However, the diuretic response to furosemide was increased in ARF rats compared with control rats. Although the relationship between the urine flow rate (UFR) and the urinary excretion rate of (Na^++K^+) (UV_<Na+K>) was the same in both groups, the urinary excretion rate of K^+(UV_K) was decreased in ARF rats. The concentrating ability in ARF rats was also decreased compared with that in control rats. By infusion of aldosterone in ARF rats, both UV_K and the concentrating ability were increased and the diuretic response to furosemide was decreased, whereas the relationship between UFR and UV_<Na+K> was not changed. Therefore, it is concluded that the increased diuretic response to urinary excretion of furosemide in ARF rats may be caused, at least in part, by the decreased concentrating ability along the nephron.