Mechanism of spasmolytic activity of a fraction of <i style="">Sarcostemma brevistigma</i> Wight

Abstract

The effect of chloroform soluble fraction (F-A) of twigs of <i style="">Sarcostemma brevistigma</i> on contractions induced by KCl, histamine, and acetylcholine in the isolated guinea pig ileum and taenia coli smooth muscles has been evaluated. F-A (19.5 µg/ml) significantly inhibited the contraction induced by 40 mM KCl to the extent of 87.6% in the isolated guinea pig ileum. In the isolated guinea pig ileum, F-A (64.3 and 59.2 µg/ml) significantly inhibited the contractions induced by acetylcholine and histamine to the extent of 85 and 83% respectively. In the isolated guinea pig taenia coli, F-A (65.2 µg/ml) significantly inhibited the contraction induced by 40 mM KCl to the extent of 96.0%. The inhibitory effect of F-A (40 µg/ml) on the isolated guinea pig taenia coli was reduced by Bay K 8644 (10^-6M) to the extent of 61.6 from 73.6%. These results suggest that the F-A may exhibit smooth muscle relaxant activity by blocking the Ca²⁺ channels.