BETA-ADRENOCEPTOR CHANGES IN MONONUCLEAR LEUKOCYTES DURING PREGNANCY

Leukocyte beta(2)-adrenoceptors mirror similar receptors in the uterus . This study examined changes in beta(2)-adrenoceptors and in cAMP pro duction during pregnancy using peripheral mononuclear leukocytes Isola ted from 17 pregnant women and 5 nonpregnant controls. beta(2)-Adrenoc eptor density was determined by I-125-pindolol binding. cAMP productio n under basal and stimulated (10 mu M isoproterenol) conditions was de termined by radioimmunoassay. Groups were compared by unpaired t test. There was a nonsignificant decrease in the density of beta-adrenocept ors during pregnancy. While basal cAMP production was unchanged during pregnancy, stimulated cAMP production was decreased (44% of control, P < 0.001;95% CI 33%-56%). stimulated cAMP production per receptor was lower in leukocytes from pregnant women and was not a constant relati onship, but was increased markedly in leukocytes having fewer than 400 beta-adrenoceptor sites per cell. There are significant changes in th e coupling of beta-adrenoceptors to cAMP production during pregnancy w ithout changes in beta-receptor density, affinity, or basal cAMP produ ction.