Sex differences in function and distribution of beta-adrenoceptors in rabbit urinary bladder.

Abstract

To examine whether there are sex-related differences in urinary bladder function, we evaluated the function and distribution of beta-adrenoceptor in the male and female rabbit urinary bladder. Ten male and ten female rabbits were studied. The function and distribution of beta-adrenoceptors were studied by measuring changes in contractile forces from isoproterenol, a beta-adrenoceptor agonist, and forskolin, an adenylate cyclase activator, and by measuring beta-adrenoceptor densities using radioligand receptor binding techniques. Isoproterenol caused significantly greater relaxation in female trigonal muscles than in male trigonal muscles. It caused similar relaxation responses in the male and female detrusors. The Bmax values for [3H]dihydroalprenolol (DHA) binding in trigonal muscles were significantly higher in the female than in the male, whereas Bmax values for [3H]DHA binding in the male and the female detrusor were similar. In contrast, forskolin caused similarly marked relaxations in the male and the female detrusor and trigonal muscles. These findings demonstrate that there are sex-related differences in the function and the distribution of beta-adrenoceptors in rabbit trigonal smooth muscles.