Effects of anesthetic doses of morphine on renal function in the dog.

Renal effects of anesthetic doses of morphine (2 mg./kg.) administered intravenously (I.V.) were determined in 15 mongrel dogs before and after addition of 50 percent nitrous oxide (N2O). Morphine significantly increased urine osmolarity and decreased urine output, free-water clearance, and arterial blood pressure, but did not affect inulin or para-aminohippurate (PAH) clearances. Addition of N2O did not significantly change arterial blood pressure and inulin clearance but did decrease urine osmolarity and osmolar and PAH clearances. These data demonstrate that, in contrast to man, anesthetic doses of morphine have significant antidiuretic properties in the dog.