A STUDY IN THE DOG OF THE RENAL CLEARANCE OF MORPHINE AND THE EFFECT OF MORPHINE ON p-AMINOHIPPURATE CLEARANCE

¹ Department of Pharmacology, University of Michigan Medical School, Ann Arbor

In normal unanesthetized female dogs the primary mechanism by which free and conjugated morphine are removed from plasma by the kidney appears to be glomerular filtration although a small amount of free morphine may be eliminated by tubular excretion. Neither subcutaneous injection of 30 mgm./kgm. of morphine nor the combination with intravenous infusion of 7.5 mgm./kgm. of morphine, both of which have minimal effects on systemic blood pressure, has any effect on the renal clearance of inulin and accordingly glomerular filtration rate. However the combination of the subcutaneous injection with the intravenous venous infusion of morphine produces an 11 to 45 per cent reduction in the clearance of p-aminohippuric acid and accordingly in apparent renal plasma flow. The maximum tubular excretion of p-aminohippuric acid is not altered by the combination of subcutaneous injection and intravenous infusion of morphine.