ISOPROTERENOL EXCRETION AND METABOLISM IN THE ISOLATED PERFUSED RAT-KIDNEY

  • 1 January 1979
    • journal article
    • research article
    • Vol. 210  (2) , 295-300
Abstract
[3H]Isoproterenol excretion and metabolism were studied in the isolated perfused rat kidney using a 1-pass, non-recirculating perfusion system with constant infusion rates of [3H]isoproterenol. The isoproterenol (urine/plasma, U/P) to inulin (U/P) ratio was approximately 15 indicating extensive tubular secretion. A major renal metabolite, 3-O-methylisoproterenol, appeared in the urine and renal vein perfusate and also accumulated in the renal tissue. The fractional excretion of isoproterenol decreased with time while the fractional excretion of p-aminohippurate remained stable. The observed decreasing urinary clearance and percent extraction of isoproterenol with time may be due to the progressive intrarenal accumulation of 3-O-methylisoproterenol. Isoproterenol is a sympathomimetic agent which acts primarily at the .beta.-receptor. It is used clinically as a cardiac stimulant in the treatment of shock and as a smooth muscle relaxant in the treatment of bronchospasm.