Vascular and renal effects of leukotriene C4 in conscious rats

To investigate the possible renal effects of leukotriene C4 (LTC4) renal function was monitored in conscious unrestrained rats. Intravenous injections of 2, 4, and 8 micrograms/kg LTC4 markedly and dose-dependently elevated urine flow (by 64, 91, and 133%, respectively) with a concomitant increase in urinary sodium (61, 81, and 118%) and potassium (39, 50, and 76%) excretion. All changes were statistically significant. There was a tendency for glomerular filtration rate to increase, but this change reached statistical significance only after the highest dose of LTC4. Moreover, 8 micrograms/kg LTC4 reduced p-aminohippurate clearance by 33%. A dose-dependent increase in mean arterial pressure (15 mmHg at 2 micrograms/kg, 20 mmHg at 4 micrograms/kg, and 30 mmHg at 8 micrograms/kg) was observed following LTC4 administration. While the administration of FPL 55712, a putative antagonist of leukotrienes, had no effect on mean arterial pressure and kidney function, it significantly attenuated the vasopressor effect of LTC4 and practically completely abolished LTC4-induced changes in both renal hemodynamics and water and electrolyte excretion. These results raise the possibility that leukotrienes might be involved in the regulation of renal hemodynamics and could modify urinary electrolyte excretion under conditions in which leukotriene formation is enhanced.