Modification of oestrogen-induced uterine hyperaemia by drugs in the ovariectomized rat

Abstract

Uterine blood flow in ovariectomized rats was measured by radioactive microspheres. Blood flow was increased from 55 ml min-1 100g-1 by treatment (i.v.) with 0.5 .mu.g estradiol kg-1 and reached 680 ml min-1 100g-1 within 60 min. This estrogen-induced increase of blood flow was significantly reduced by pretreatment with mepyramine (a histamine H1-receptor antagonist), cellulose sulfate ( a kininogen-depleting agent) and aprotinin (a kininogenase inhibitor). Cimetidine (a histamine H2- receptor antagonist), kallikrein (kininogenase enzyme) and atropine (an anticholinergic drug) had no effect on the increased uterine blood flow. Indomethacin and AH 7170, which inhibit the formation of prostaglandins, also caused a lower increase in uterine blood flow. None of the pretreatments fully inhibited the estrogen-induced increase in blood flow, suggesting that more than 1 mediator may be involved.