Keshavarz M, Karimian S, Dehpoor A, Parviz M. The effect of Dopamine receptor agonists on twich response of Guinea-pig ileum longitudinal muscle and its relation to Nitric Oxide. Tehran Univ Med J 1998; 56 (6) :6-10
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http://tumj.tums.ac.ir/article-1-1498-en.html
Abstract: (11369 Views)
In this study the effects of bromocriptine and apomorphine (dopamine receptor agonists) on electrical field induced twitch response of longitudinal muscle of guinea-pig illeum was investigated. Bromocriptine and apomorphine dose dependently inhibited illeal contraction. IC50 for this inhibitory effects were 6.22±0.645×10^-7 M and 5.48±0.647×10^-6 M, respectively. sulpiride (a specific D2 dopamine receptor antagonist) with concentration of 10^-5 M inhibited the effects of these agonists. Yohimbine (an ?2 adrenergic receptor antagonist) only blocked the inhibitory effect of bromocriptine but failed to block apomorphine inhibitory effects. L-NAME (nitric oxide synthetase inhibitor) with concentration of 10^-3 M blocked the effects of bromocriptine and apomorphine. These data suggest that there is inhibitory presynaptic dopamine receptors in cholinergic terminals of guinea-pig ileum and its function is related to formation of nitric oxide.