Prirded in U.S.A.

MAY, DAVID G., Jtasss M. Fusnso’ro rp Cuuti.zs E. IruiwIsI: The tubular transport and metabolism of morphine-N-methyl-C1 ’ by the chicken kidney. J. Pharmacol. Exp. Therap. 157: 626-635, 1967. The renal portal system of chickens was utilized to study the renal tubular transport and renal metabolism of morphine. An average apparent tubular excretion fraction of 29.5 % was found for excreted radioactivity when tracer doses of morphine-Ca ’ were infused and an average apparent tubular excretion fraction of 13.6% was determined for excreted radioactivity when 035 mg/kg/mm of unlabeled morphine sulfate was infused with the tracer. The nature of the excreted radioactivity was charac-terized by countercurrent distribution analyses. Two components were excreted, free morphine-C1 ’ and a C ” metabolite. The metabolite was also excreted in excess by the infused kidney, which indicated that the metabolite had been formed by the kidney. Apparent tubular excretion fractions greater than 10 % were found for the excreted free morphine. Cyanine 863, which blocks the base transport system, reduced the excretion of both free morphine and metabolite by the the infused kidney. Experiments using increas