S-Space College of Medicine/School of Medicine (의과대학/대학원) Dept. of Medicine (의학과) The Seoul Journal of Medicine The Seoul Journal of Medicine Vol. 32 No.4 (1991)
Effects of Dopamine on the Contractility of the Circular Muscles in the Guinea-pig Gastric Antrum and Fundus : 도파민이 기니피그 위 유문동과 위저부 윤상근의 수축성에 미치는 효과
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- Issue Date
- Seoul J Med, Vol.32 No.4, pp. 199-207
- Dopamine ; Antral and fundic circular muscles ; alpha-adrenergic receptor ; Non-adrenergic noncholinergic nerves
- The effects of dopamine on gastric motility were investigated using circular
muscle strips prepared from the antral and' fundic regions of the guinea-pig stomachs.
The spontaneous and phasic contractions induced by electrical stimulation were recorded
with a force transducer. Dopamine potentiated the spontaneous contraction of the
antral circular muscle, which was suppressed completely by a-blocker phentolamine
and partially by a2-blocker yohimbine but was not blocked by TTX. Dopamine increased
the basal tone of both the antral and the fundic circular muscles, which was suppressed
by phentolamine but not affected by TTX. Dopamine increased the contraction evoked
by direct electrical stimulation to the fundic circular muscle, which was suppressed
by phentolamine but unaffected by TTX. Dopamine increased the basal tone and relaxation
component of the phasic contraction evoked by transmural nerve stimulation in
the fundic region, while it decreased the contraction component. Atropine decreased
the contraction component in the fundic region, while it increased the relaxation component.
In the presence of atropine dopamine increased the basal tone and relaxation
component, which were suppressed by phentolamine.
In conclusion, dopamine increases the basal tone of both the antral and fundic circular
muscles and the amplitude of spontaneous contraction of the antral circular muscle
via a-adren-ergic receptors, especially via the ai-receptor in the plasma membrane of
circular muscle cells. Dopamine increases the relaxation component through the enhanced
release of transmitters from non-adrenergic non-cholinergic nerve terminals, and
suppresses contraction by inhibiting transmitter release from cholinergic nerves in the
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