Regional differences in vascular responses in the human uterus

Summary. Tissue specimens from the fundus, isthmus and distal cervix were obtained from 14 women at hysterectomy at various phases of the menstrual cycle. Ring preparations of small intramyomctrial and intracervical arteries were dissected and mounted in organ baths; isometric tension was recorded and responses to contractile agents were studied. The amplitude of responses to K⁺ (124mmol/l) of the vessel preparations ranked fundus isthmus > cervix. While similar pD₂ values for noradrenaline (NA) were found, the E_max values ranked cervix isthmus fundus (cervix > fundus). The pD₂ values for arginine-vasopressin (AVP) showed minor differences, while the E_max values for this peptide ranked fundus isthmus cervix (fundus > cervix). Arteries from the fundus and isthmus displayed weak, inconsistent contractile responses to prostaglandin F_2α, but more pronounced contractions were induced by this prostanoid in arterial preparations from the distal cervix. The results suggest regional differences in vascular mechanical responses to endogenous vasoactive agents in the human uterus.