Effect of furosemide on renal hilar lymph flow

Furosemide is known to increase total renal blood flow. The purpose of this study was to determine the relationship between this hemodynamic change and renal hilar lymph flow. Renal blood flow was measured with an electromagnetic flowmeter placed on the left renal artery of anesthetized dogs. Lymph was collected from a cannulated hilar vessel. Urine volume loss was not replaced. In the first 10 min after furosemide (1 mg/kg i.v.), lymph flow was significantly increased and then declined toward control within 30 to 40 min. The decline in lymph flow lagged behind the decline in blood flow by about 10 min. In 11 experiments in which there was a significant increase in renal blood flow, renal hilar lymph flow also increased. In 5 experiments in which renal blood flow did not increase after furosemide, lymph flow also did not increase. In both groups, urine volume was significantly increased but the diuresis was less in the group in which renal blood flow and lymph did not increase. When hydrochlorothiazide (5 mg/kg, i.v.) was administered, neither renal blood flow nor hilar lymph flow was altered. The effect of equi-diuretic doses of furosemide and hydrochlorothiazide on renal tissue water content were compared. The amount of water present after furosemide was significantly greater than the amount present after hydrochlorothiazide. These data support the concept that changes in renal hilar lymph flow are more a consequence of changes in renal blood flow than in urine volume.