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Role of the T‐type calcium channel in the spontaneous phasic contraction of pregnant rat uterine smooth muscle
Author(s) -
Lee Sieun,
Ahn Ducksun,
Kang Boksoon,
Lee Youngho
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1206.10
Subject(s) - mibefradil , nifedipine , myometrium , medicine , contraction (grammar) , endocrinology , channel blocker , chemistry , l type calcium channel , calcium channel , t type calcium channel , voltage dependent calcium channel , calcium channel blocker , uterine contraction , calcium , biophysics , uterus , biology
We investigated the role of the T‐type Ca 2+ channel in spontaneous phasic contraction (SPC) of the rat myometrium. SPC and [Ca 2+ ] i were measured simultaneously in longitudinal strips of female rats in late pregnancy. Expression of T‐type Ca 2+ channel subunits was examined by using RT‐PCR technique. The SPC and [Ca 2+ ] i were completely inhibited by removal of external Ca 2+ and treatment of nifedipine. T‐type Ca 2+ channel blocker, 1μM mibefradil and 5μM NNC 55‐0396 evoked concentration‐dependent inhibition of SPC and [Ca 2+ ] i and these blockers decreased the amplitude and frequency of SPC as well as [Ca 2+ ] i . On the other hand, 100μM nickel, a blocker of T‐type Ca 2+ channel, decreased the frequency but not the amplitude of SPC. Pretreatment of mibefradil and NNC 55‐0396 significantly attenuated the KCl‐induced increase in contraction and [Ca 2+ ] i , respectively, but nickel had no effect on KCl‐induced increase in contraction and [Ca 2+ ] i . All of three T‐type Ca 2+ channel blockers decreased the slope of rising phase of SPC and [Ca 2+ ] i . In RT‐PCR analysis, T‐type Ca 2+ channel subunits, Cav3.1 and Cav3.2, were expressed in pregnant rat myometrium. The present study demonstrates that T‐type Ca 2+ channel involves in the generation of SPC of pregnant rat myometrium. Furthermore, Ca 2+ influx through T‐type Ca 2+ channel may play a key role for the slow depolarization.