Studies on the Intracellular Distribution and Tissue Binding of Dihydromorphine-7,8-H3 in the Rat

Abstract

Summary Dihydromorphine-7,8-H³ of high specific activity was prepared by the catalytic tritriation of the double bond of morphine and purified. Studies of the intracellular distribution of radioactivity in the brains and livers of rats injected with the labeled drug showed that most of it was in the soluble fraction. However, the brain nuclear fraction consistently contained 10-20% of the radioactivity of the homogenate. The administration of nalorphine had no effect on tissue levels or intracellular distribution. Binding of dihydromorphine to brain and liver homogenates and to serum proteins was demonstrated by equilibrium dialysis. The degree of binding was similar in the different tissues and not affected by the addition of nalorphine. Tissue homogenates from morphine-tolerant rats exhibited the same amount of binding as those from control rats.