UTERINE BETA-ADRENERGIC RECEPTORS IN ALLOGENEIC AND SYNGENEIC PREGNANCY

Two different mechanisms of regulation in uterine beta-adrenergic rece ptors in allogeneic pregnancy (AP) and syngeneic pregnancy (SP) are de scribed in this work. Firstly we noted changes in beta-adrenergic sens itivity to isoproterenol in AP, while in SP differences in uterine rea ctivity to isoproterenol were found. In binding assays with the beta-a ntagonist [H-3]dihydroalprenolol, changes in beta-receptor affinity we re seen in AP, while in SP the maximal number of binding sites is alte red. In addition, there are differences in uterine concentrations of c yclic AMP in both types of pregnancies as well as in the nucleotide re sponse to isoproterenol. The differences in the reactivity and express ion of uterine P-adrenoceptors in both types of pregnancies may be due to a distinctive immunological role of the semiallogeneic fetus in AP .