The effect of the oxytocin antagonists, CAP 476 and F327, on calcium mobilisation in single cultured human myometrial cells.
OBJECTIVE
To investigate the mechanism of action of the oxytocin (OT) antagonists, CAP 476 and F327.


METHODS
A prospective descriptional study.


METHODS
Women undergoing caesarean section at term or hysterectomy.


METHODS
Myometrial cells were cultured from uterine biopsies.


METHODS
Intracellular calcium ([Ca2+]i), determined in single cells.


RESULTS
Application of OT caused a transient increase in [Ca2+]i. CAP 476 abolished and F327 reduced the response to OT but neither reduced the [Ca2+]i transient induced by cell depolarisation with 120 mmol K+. CAP 476 did not reduce transients caused by prostaglandin E2. F327 reduced the frequency of repetitive [Ca2+]i transients occurring during continuous application of OT.


CONCLUSIONS
The results demonstrate that the antagonists reduce the effect of OT and that their action is relatively specific. Their mechanism of action as clinical tocolytic agents is discussed.
Thornton
S
S
Department of Obstetrics and Gynaecology, Princess Mary Maternity Hospital, Newcastle upon Tyne.
Gillespie
J I
JI
Anson
L C
LC
Greenwell
J R
JR
Melin
P
P
Dunlop
W
W
D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D002585:Cesarean Section; D005260:Female; D006801:Humans; D007044:Hysterectomy; D009215:Myometrium / Q000187:drug effects / Q000378:metabolism*; D010121:Oxytocin / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D011247:Pregnancy; D011446:Prospective Studies; D014668:Vasotocin / Q000031:analogs & derivatives* / Q000494:pharmacology
D015220:Calcium Channels; C047046:atosiban; C082249:F 327; D010121:Oxytocin; D002118:Calcium; D014668:Vasotocin