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KMID : 0374919950160010147
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Inje Medical Journal
1995 Volume.16 No. 1 p.147 ~ p.156
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A Study on the Phasic and the Tonic Contraction in the Corpus Smooth Muscle of Cuinea-Pig Stomach
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Abstract
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The effects of nifedipine, extracellular Ca+. K+ concentration and TEA(Tetraethylammonium) on the phasic contractionand tonic contraction were stuidied in order to elucidate Ca2+ mobilization related with phasic contraction and tonic contraction
respectively in the corpus muscle of guinea-pig stomach Spontaneous contractions were suppressed by nifedipine (10E7-10-6M) but the tonic component of the basal activity was not suppressed. Acetylcholine-induced contracture was composed of
repetitive
phasic component and a tonic component abd the repetitive phasic component was inhibited by nifedipine 10E6M but tonic component was resistant to nifedipine. The development of the tonic component was dependent on the extracellular Ca2+
concentration.
The magnitude of the spontaneous contractions and tonic basal component were increased by TEA. The magnitudes of the phasic and the tonic components were larger in the 60 mM K+-contracture and the phasic component relatively increased more than
the
tonic component.
From above all the results it is suggested that the phasic contraction is developed by Ca2+ influx through nifedipine-resistant Ca2+-channel and the phasic contraction is more dependent on the electric excitability of the cellular membrane than
the
tonic conraction.
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