Oxytocin inhibits T-type calcium current of human decidual stromal cells.
BACKGROUND
Little is known about the crosstalk between the decidua and myometrium in relation to human labor. The hormone oxytocin (OT) is considered to be a key mediator of uterine contractility during parturition, exerting some of its effects through calcium channels.


OBJECTIVE
The objective was to characterize the effect of OT on the T-type calcium channel in human decidual stromal cells before and after the onset of labor.


METHODS
The nystatin-perforated patch-clamp technique was used to record inward T-type calcium current (I(Ca(T))) from acutely dispersed decidual stromal cells obtained from women at either elective cesarean section [CS (nonlabor)] or after normal spontaneous vaginal delivery [SVD (labor)].


METHODS
These studies took place at the University of Nottingham Medical School.


RESULTS
I(Ca(T)) of both SVD and CS cells were blocked by nickel (IC(50) of 5.6 microm) and cobalt chloride (1 mm) but unaffected by nifedipine (10 microm). OT (1 nm to 3.5 microm) inhibited I(Ca(T)) of SVD cells in a concentration-dependent manner, with a maximal inhibition of 79.0% compared with 26.2% in decidual cells of the CS group. OT-evoked reduction of I(Ca(T)) was prevented by preincubation with the OT antagonist L371,257 in the SVD but not CS group. OT, in a concentration-dependent manner, displaced the steady-state inactivation curve for I(Ca(T)) to the left in the SVD group with no significant effect on curves of the CS group.


CONCLUSIONS
Inhibition of I(Ca(T)) by OT in decidual cells obtained during labor may signify important functional remodeling of uterine signaling during this period.
Liu
Bo
B
Institute of Cell Signalling, University of Nottingham, Queens Medical Centre, Nottingham, United Kingdom.
Hill
Stephen J
SJ
Khan
Raheela N
RN
D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020747:Calcium Channels, T-Type / Q000187:drug effects*; D002469:Cell Separation; D003656:Decidua / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D010121:Oxytocin / Q000494:pharmacology*; D017154:Stromal Cells / Q000187:drug effects
D002121:Calcium Channel Blockers; D020747:Calcium Channels, T-Type; D010121:Oxytocin