Effects of the water soluble fraction from leaves of Ageratum conyzoides on smooth muscle

The water soluble fraction of Ageratum conyzoides L, (WSF) wars studied in isolated rat uterus and intestinal smooth muscles in order to evaluate its popular use as a spasmolytic. WSF (0.2 and 0.4 mg/mL) increased EC50 values and decreased maximum responses to acetylcholine and calcium chloride. WSF (0.5-3.3 mg/mL) also produced direct myorelaxant effect on smooth muscle p reparations, Theophylline (10(-3) M) potentiated the relaxant action of WSF , Theophylline also prevented the decrease in maximum response promoted by WSF in acetylcholine concentration-effect curves. These results seem to be partially linked to calcium mobilization, The data also suggest that WSF co uld act synergistically with theophylline in the inhibition of cyclic AMP p hosphodiesterase, The results give support to the popular medicinal indicat ions of the plant. Copyright (C) 2000 John Wiley & Sons, Ltd.