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KMID : 0356219950260010075
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Journal of the Korean Military Medical Association
1995 Volume.26 No. 1 p.75 ~ p.83
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The Effects of Noradrenaline on the Gastric Motility in Guninea-Pig
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Abstract
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It is well known that the spontaneous contractions of gastointestinal smooth muscles are generated by the myogenic slow waves and are modulated by autonomic nervous system and circulating hormones. Noradrenaline is m
ajor neurotransmitler of
sympathetic
nervous system and secreted in adrenal gland by stress.
To investigate the effects of noradrenaline on the gastric motility and its action mechanisms we recorded electrical slow waves and membrane currents in the antral circular muscle strips of guineapig and in the enzymatically dispersed myocytes
respectively.
Noradrenaline hyperpolarized the membrane potential of antral smooth cells and increased the amplitude and the maximum rate of rise of slow waves. Also, noradrenaline produced action potentials on the top of slow waves. At the same time, both
tonic
and
phasic contractions were increased. The changes of slow waves and increased mechanical contractions induced by noradrenaline were completely antagonized by the administration of phentolamine, a bloker of a-receptor, Noradrenaline increased
voltage-dependent Ca2+ currents in the whole test voltage and were antagonized by phentolamine.
From these results, it could be suggested that excitatory action to noradrenaline is mediated by the modulation of voltage-dependent Ca2+ channel through a-receptor.
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