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KMID : 0811720060100000334
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Korean Journal of Physiology & Pharmacology
2006 Volume.10 No. 0 p.334 ~ p.0
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EFFECTS OF PH CHANGE ON SPONTANEOUS CONTRACTION AND IONIC CURRENTS PREGNANT RAT UTERINE SMOOTH MUSCLE
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Kim Young-Hwan
Lee Si-Eun
Lee Young-Ho
Ahn Duck-Sun
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Abstract
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This study was designed to determine the effects of intracellular pH change on spontaneously phasic contractions of rat uterine smooth muscle. Uterine smooth muscle was obtained in rats at 18～20 days of gestation. Longitudinal strips were dissected and loaded with the calcium sensitive indicator Fura-2/AM. Patch-clamp technique on isolate longitudinal muscle cell was used. In spontaneously phasic contractions, the application of ammonium chloride caused a marked increase in the frequency and amplitude of phasic contractions. In some preparations, ammonium chloride caused tonic contractions. The force was associated with corresponding increase in the [Ca2+]i transients. The addition of sodium acetate to spontaneously phasic contractions produced a brief abolition of phasic contractions, followed by decreased phasic contractions. Intracellular or extracellular acidosis (20 mM Na+ acetate or pH 6.9) decreased the magnitude of the calcium current. However, the intracellular or extracellular alkalosis (20 mM NH4Cl or pH 7.9) increased the magnitude of the calcium current. Intracellular alkalosis decreased the delayed rectifier K+ current but intracellular acidosis increased the delayed rectifier K+ current. However extracellular alkalosis (pH 7.9) inecreased the delayed rectifier K+ current and extracellular acidosis (pH 6.9) decreased the delayed rectifier K+ current. These results indicate that pH-dependent change in Ca2+ channel and K+ channel may be involved in the pH-dependent modulation of phasic contraction.
Source: Korean J Physiol Pharmacol.2006 Oct;10(Suppl II):243
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KEYWORD
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uterine smooth muscle, pH, Ca2+ current, K+ current
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