Abstract
This study was performed to evaluate the in vitro effects of a new polypeptide, endothelin-1 (ET-1) on small intramyometrial vessels in comparison with the action of noradrenalin (NA). In connection with cesarean section, myometrial biopsies were obtained and small arteries (100–500 um in diameter) were excised. Cylindrical segments of these vessels were used for registration of contractile activity after administration of ET-1 and NA. ET produced vasoconstriction and was approximately three times as powerful and 70-fold as potent as NA. It is suggested that ET may be involved in the regulation of human utero-placental blood flow.