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KMID : 0358619930270020139
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Korean Journal of Physiology
1993 Volume.27 No. 2 p.139 ~ p.150
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Effect of Dopamine on the in Isolated Single Gastric Myocytes of the Guinea-pig
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Rhee Poong-Lyul
Lee Sang-Jin
Kim Sung-Joon
So In-Suk
Hwang Sang-Ik
Kim Ki-Whan
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Abstract
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We have reported that dopamine potentiates spontaneous contractions dose-dependently in guinea-pig antral circular muscle strips (Hwang et al, 1991). To clarify the underlying excitatory mechanism of dopamine on the gastric smooth muscle, the effects of dopamine on voltage-dependent were observed in enzymatically dispersed guinea-pig gastric myocytes using the whole-cell voltage-clamp technique. Experiments were also done using isometric tension recording and conventional intracellular microelectrode techniques. 1) The effect of dopamine on the spontaneous contraction of antral circular muscle strips of the guinea-pig was excitatory in a dose-dependent manner, and was blocked by phentolamine, an blocker. 2) The slow waves were not changed by dopamine. 3) The voltage-operated inward current was not influenced by dopamine. 4) The outward current, which might reflect the changes of intracellular calcium concentration, was enhanced by dopamine. This effect was abolished by phentolamine. 5) The enhancing effect of dopamine on the current disappeared with heparin which is known to block the action of . From these results, it is suggested that dopamine acts via mobilization from intracellular stores and such action potentiates the spontaneous contraction of guinea-pig gastric smooth muscle.
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KEYWORD
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Dopamine, Smooth muscle, Inositol trisphosphate, Calcium-dependent potassium current
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