TY - JOUR T1 - DISTRIBUTION OF N-C<sup>14</sup>-METHYL LABELED MORPHINE: II. EFFECT OF NALORPHINE IN THE CENTRAL NERVOUS SYSTEM OF NONTOLERANT DOGS AND OBSERVATIONS ON METABOLISM JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 242 LP - 249 VL - 136 IS - 2 AU - S. J. Mulé AU - L. A. Woods AU - L. B. Mellett Y1 - 1962/05/01 UR - http://jpet.aspetjournals.org/content/136/2/242.abstract N2 - The subcutaneous administration of labeled morphine prior to nonlabeled nalorphine resulted in a significant increase in the CNS levels of morphine in nontolerant dogs. Simultaneous injection of both drugs, or pretreatment with nalorphine resulted in an increase or no change in the CNS levels of morphine in nontolerant dogs as compared with the morphine control dog values. The effect of nalorphine on the plasma and cerebrospinal fluid concentrations of free morphine was somewhat variable. Paper chromatographic studies provided no evidence for the presence of an N-C14-methyl labeled metabolite of morphine in the CNS and urinary extracts of nontolerant and tolerant dogs. ER -