Role of T-type Ca2+ Channels in the Spontaneous Phasic Contraction of Pregnant Rat Uterine Smooth Muscle
The Korean Journal of Physiology and Pharmacology
;
: 241-249, 2009.
Article
in English
| WPRIM
| ID: wpr-727528
ABSTRACT
Although extracellular Ca2+ entry through the voltage-dependent Ca2+ channels plays an important role in the spontaneous phasic contractions of the pregnant rat myometrium, the role of the T-type Ca2+ channels has yet to be fully identified. The aim of this study was to investigate the role of the T-type Ca2+ channel in the spontaneous phasic contractions of the rat myometrium. Spontaneous phasic contractions and [Ca2+]i were measured simultaneously in the longitudinal strips of female Sprague-Dawley rats late in their pregnancy (on day 18~20 of gestation term=22 days). The expression of T-type Ca2+ channel mRNAs or protein levels was measured. Cumulative addition of low concentrations (<1 micrometer) of nifedipine, a L-type Ca2+ channel blocker, produced a decrease in the amplitude of the spontaneous Ca2+ transients and contractions with no significant change in frequency. The mRNAs and proteins encoding two subunits (alpha1G, alpha1H) of the T-type Ca2+ channels were expressed in longitudinal muscle layer of rat myometrium. Cumulative addition of mibefradil, NNC 55-0396 or nickel induced a concentration-dependent inhibition of the amplitude and frequency of the spontaneous Ca2+ transients and contractions. Mibefradil, NNC 55-0396 or nickel also attenuated the slope of rising phase of spontaneous Ca2+ transients consistent with the reduction of the frequency. It is concluded that T-type Ca2+ channels are expressed in the pregnant rat myometrium and may play a key role for the regulation of the frequency of spontaneous phasic contractions.
Full text:
Available
Index:
WPRIM (Western Pacific)
Main subject:
Benzimidazoles
/
RNA, Messenger
/
Nifedipine
/
Calcium Channels
/
Proteins
/
Rats, Sprague-Dawley
/
Mibefradil
/
Cyclopropanes
/
Contracts
/
Muscle, Smooth
Limits:
Animals
/
Female
/
Humans
/
Pregnancy
Language:
English
Journal:
The Korean Journal of Physiology and Pharmacology
Year:
2009
Type:
Article
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