In vitro contractility of human umbilical artery

Action of Alpha-Methyldopa on Human Umbilical Circulation in vitro

“…A 3-cm portion of umbilical artery was dissected, cannulated with a polyethylene catheter and placed in a 10-ml chamber containing nutrient solution aerated with 95% Cb and 5% CO:. The perfusion technique, which has been described in detail by Meirelles et al [6], is based on changes in the resistance of the vascular segment in a perfu sion system at constant flow, evaluated by pressure measurements.…”

Estriol Antagonism of the Action of Bradykinin and Adrenalin on Human Umbilical Artery

“…Its effect on uterine contractility (9) led investigators to formulate tire hypothesis of its participation in uterine physiology and fetal-placental circulation. The vasoconstricting action of bradykinin on the umbilical circulation has already been described by Melmon et al (11) and Meirelles et al (10). On the other hand, sympathomimetic amines are classically employed agents in investigations on the reactivity of isolated vessels (5,10), and a relevant role has been attributed to them in the regulation of umbilical circulation (4).…”

“…The vasoconstricting action of bradykinin on the umbilical circulation has already been described by Melmon et al (11) and Meirelles et al (10). On the other hand, sympathomimetic amines are classically employed agents in investigations on the reactivity of isolated vessels (5,10), and a relevant role has been attributed to them in the regulation of umbilical circulation (4). These findings may have a physiological significance for they provide evidence for a role of estrogens, and estriol in particular, in the modulation of the response of this vascular bed to various chemical stimuli, in a way similar to that observed for the uterine vessels (3).…”

“…A 3-cm portion of umbilical artery was dissected, cannulated with a polyethylene catheter and placed into a 10-ml chamber. The perfusion technique has been described by Meirelles et al (10). The perfusion system consisted of a continuous infusion pump, a 20-or 50-ml glass syringe, a glass coil, a glass T-tube, a 2-cm long PE-160 polyethylene catheter, and a 3-cm vascular segment with a 0.15-mm diameter nylon thread running through the full length of its lumen.…”

“…The three natural estrogens (estradiol, estrone and estriol) have a relaxing effect on the human umbilical cord perfused in vitro (15). On this basis, it may be presumed that estrogens may constitute one more regulating factor of the reactivity of human umbilical artery in addition to gases, temperature, pH, mechanical stimuli, and a few vasoactive substances, most notably adrenalin and bradykinin (4,10,11,13).…”