Reduced beta 2-adrenoceptor sensitivity in normal pregnancy but not in pregnancy-induced hypertension.
beta 2-Adrenoceptors on lymphocytes from healthy nonpregnant and pregnant women and patients with pregnancy-induced hypertension (PIH) were studied in vitro by a radioligand binding technique (125I-hydroxybenzylpindolol) and related to in vivo responses to infused adrenaline. Healthy pregnant women had significantly fewer beta 2-adrenoceptor binding sites than nonpregnant controls (47.1 +/- 5.6 vs. 73.6 +/- 10.5 fmol X mg-1 protein), PIH patients displaying intermediate values. Adrenaline-induced increases in plasma cyclic AMP (a beta 2-mediated in vivo response) also tended to be reduced during normal pregnancy. The systemic vasodilatation evoked by intravenously infused adrenaline and the density of lymphocyte beta 2-adrenoceptor binding sites were positively related in the nonpregnant controls (r = 0.50), but inversely related in both the pregnant controls (r = -0.40) and the PIH patients (r = -0.70). These regression lines differed significantly. The present results indicate a reduction of beta 2-adrenoceptor function during normal pregnancy, which is less pronounced in PIH, as well as an altered relationship between beta 2-mediated vasodilator responses and densities of beta 2-adrenoceptors on lymphocytes during pregnancy.
Nisell
H
H
Department of Obstetrics and Gynecology, Huddinge University Hospital, Sweden.
Martinsson
A
A
Hjemdahl
P
P
D002499:Centrifugation, Density Gradient; D000242:Cyclic AMP / Q000097:blood; D004837:Epinephrine / Q000097:blood; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood*; D008214:Lymphocytes / Q000378:metabolism*; D011247:Pregnancy / Q000097:blood*; D011249:Pregnancy Complications, Cardiovascular / Q000097:blood*; D011869:Radioligand Assay; D011943:Receptors, Adrenergic, beta / Q000097:blood*
D011943:Receptors, Adrenergic, beta; D000242:Cyclic AMP; D004837:Epinephrine