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
em En
| WPRIM
| ID: wpr-727528
Biblioteca responsável:
WPRO
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.
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Índice:
WPRIM
Assunto principal:
Benzimidazóis
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RNA Mensageiro
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Nifedipino
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Canais de Cálcio
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Proteínas
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Ratos Sprague-Dawley
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Mibefradil
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Ciclopropanos
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Contratos
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Músculo Liso
Limite:
Animals
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Female
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Humans
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Pregnancy
Idioma:
En
Revista:
The Korean Journal of Physiology and Pharmacology
Ano de publicação:
2009
Tipo de documento:
Article