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4-Aminopyridine on the spontaneous contractions of isolated intestine
Abstract:
The effects of 4-aminopyridine on isolated spontaneously active segments of rabbit jejunum were studied. The drug produced a dose-dependent increase of the tonic and phasic components of the contractile activity with an ED50 of 2 x 10(-5) M, lower than the reported dose for striated muscle. No effects were observed on the frequency of contractions at the concentrations of 4-aminopyridine used in this study. The results suggest both, an effect on the jejunal innervation and a direct action of the drug on the intestinal smooth muscle. The former mechanism includes the release of acetylcholine and is partially blocked by atropine. Direct effects of 4-aminopyridine on intestinal smooth muscle cells can be present at relatively low doses and they must be carefully evaluated during the suggested therapy of several human diseases with 4-aminopyridine.
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