The diuretic effect of morphine in the chicken

Abstract

The unilateral infusion of morphine 0.35 mg/kg/min into the renal portal circulation of the chicken produces a bilateral increase in urine volume, sodium and potassium excretion. The urine excretion is increased five-fold while sodium and potassium excretion are doubled. The peak diuresis occurs 5 to 15 min after the cessation of morphine infusion. Although the responses are bilateral, the infusion of C14-morphine indicates that the renal portal system is functional and that morphine is handled mainly by the infused kidney. The systemic infusion of morphine via the wing vein also produces the same results as renal portal administration. A second dose of morphine produces a diuretic effect which is much less than seen after the first dose. Rehydration of the chicken prior to the second dose of morphine does not alter this effect. Nalorphine given together with morphine completely blocks the morphine-induced diuresis, while nalorphine alone does not alter the urine flow. The delay in effect and bilateral nature of the response suggests that morphine may act through a hormonal mechanism to produce a diuresis, rather than by a direct action on the kidney tubules.