Effects of endothelins on mechanical activity and inositol phosphate production in pregnant rat myometrium.
Endothelins (ETs) caused concentration-dependent contraction in pregnant rat myometrium. ET-2 was as potent as ET-1 in affecting contractile responses, whereas ET-3 was considerably less potent than ET-1 or ET-2. ETs also increased inositol phosphate (IP) production in a dose-dependent manner, with IP production paralleling the contractile response. The rank order of potency for both the contractile responses and IP production was ET-1 = ET-2 > ET-3. When we compared the important oxytocic agent oxytocin, we found that oxytocin (10(-7) M) strongly increased contractility and IP production, and the responses were comparable to those elicited by ET-1 (10(-7) M) and ET-2 (10(-7) M). These results suggest that ET-induced myometrial contraction involves phospholipase C activation, and that a subtype of endothelin receptor existing in pregnant rat myometrium could be classified as ETA.
Okawa
T
T
Department of Obstetrics and Gynecology, Fukushima Medical College, Japan.
Suzuki
H
H
Endo
C
C
Suzuki
Y
Y
Hoshi
K
K
Sato
A
A
Nakanishi
H
H
D000818:Animals; D001696:Biomechanical Phenomena; D016232:Endothelins / Q000494:pharmacology*; D005260:Female; D007295:Inositol Phosphates / Q000096:biosynthesis*; D007700:Kinetics; D009215:Myometrium / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar
D016232:Endothelins; D007295:Inositol Phosphates