Role of polyamines in regulation of uterine blood flow of ovariectomized rats.
Polyamines have been shown to relax several types of smooth muscle including vasculature. In the estrogen-treated uterus, uterine blood flow and polyamine levels in the uterus are increased. The relaxant effect of polyamines on blood vessels suggest that polyamines may act on uterine vasculature to cause uterine hyperemia. In this study, we examined the roles of polyamines in regulating uterine blood flow. Ovariectomized rats were administered with polyamines or estrogen. The uterine blood flow was then measured by employing radioactive microspheres. The direct injection of polyamines into systemic circulation caused a 3-fold increase in uterine blood flow within 30 seconds. The polyamine-induced uterine hyperemia was counteracted by increasing extracellular calcium concentration. When rats were treated with estradiol, uterine blood flow increased. However, the treatment with alpha-difluromethylornithine, a polyamine synthesis inhibitor, did not attenuate the estrogen-induced uterine blood flow. Our results suggest that polyamines may affect uterine blood flow via antagonizing the entry of extracellular calcium. However, the detailed mechanisms via which polyamines involved in estrogenic stimulation of uterine hyperemia may require further studies.
Wing
L Y
LY
Department of Physiology, National Cheng Kung University Medical College, Taiwan, Republic of China.
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D002413:Cations, Divalent; D000518:Eflornithine / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D010052:Ovariectomy; D011073:Polyamines / Q000097:blood / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012039:Regional Blood Flow / Q000187:drug effects; D014599:Uterus / Q000098:blood supply* / Q000187:drug effects
D002413:Cations, Divalent; D004967:Estrogens; D011073:Polyamines; D004958:Estradiol; D002118:Calcium; D000518:Eflornithine