Muscle Relaxant Effects of a talantia roxburghiana on Intestinal Smooth Muscle

Abstract

The effect of a chloroform extract of Atalantia roxburghiana was investigated on contractions of smooth muscles derived from the longitudinal muscle of the ileum and the taenia coli of the guinea-pig. In the ileal longitudinal muscle, the extract demonstrated dose-dependent inhibition of electrically stimulated twitches and contractions evoked by acetylcholine, histamine, or KCl. The concentration-response curves to both acetylcholine and histamine were markedly depressed by the extract. Increasing the CaCl₂ concentration from 1.5 to 7.5 mM attenuated the inhibitory effect of the extract on tonic but not phasic contractions induced by KCl. Similarly, addition of the extract (0.5 and 0.25 mg/ml) inhibited the concentration-response curve induced by CaCl₂ in the taenia muscle which is directly related to the influx of calcium. These results indicate the relaxant effect of the chloroform extracts of Atalantia roxburghiana is postjunctional in origin, mainly due to inhibition of calcium influx through the calcium channel of the cell membrane.

Keywords::

• Atalantia roxburghiana
• Guinea-pig
• smooth muscles
• acetylcholine
• histamine
• calcium