PREGNANCY ATTENUATES ACTIVITY OF THE BARORECEPTOR REFLEX

1. Pregnancy-induced changes in acute blood pressure regulation are re viewed. 2. Pregnant animals are less able to maintain arterial pressur e during haemorrhage than non-pregnant animals. 3. Baroreceptor reflex -mediated increases in heart rate, renal sympathetic activity, vasopre ssin, ACTH and cortisol are reduced during pregnancy. Therefore, one e xplanation for the subnormal ability of pregnant animals to regulate a rterial pressure during haemorrhage is that the baroreceptor reflex is not as effective. 4. Chronic increases in oestrogen levels in non-pre gnant rabbits do not reduce the gain of baroreflex control of renal sy mpathetic activity. This and other findings suggest that oestrogen alo ne does not mediate the blunted baroreflex activity observed during pr egnancy.