Spasmolytic effect of root and aerial parts extract of Pycnocycla spinosa on neural stimulation of rat ileum

Extract prepared from aerial part of Pycnocycla spinosa is a relaxant of rat ileum contractions. The objective of this research was to study the spasmolytic activity of P. spinosa root extract for comparison with the aerial part extract. Hydroalcoholic extracts were prepared by percolation method. A portion of rat ileum was removed and suspended under 1 g tension in Tyrode's solution at 37 °C and gassed with O(2). Isotonic contractions induced by electrical field stimulation (EFS), and KCl were recorded before and after addition of the extracts. Experiments were performed alongside time-matched vehicle controls. Both EFS responses are blocked by lidocaine (74 μM), indicating that contractile responses are mediated by neuronal mechanism and partially was blocked by atropine. The root extract of P. spinosa (10-320 μg/ml) inhibited both initial rapid (IC(50) = 71 ± 11.9 μg/ml) and secondary slow contraction (IC(50) = 56 ± 7.8 μg/ml) evoked by EFS (n=6) as well as the KCl response (IC(50) = 59 ± 11.7 μg/ml). The aerial part extract had a similar inhibitory effect on both KCl (IC(50) = 47 ± 6.3 μg/ml) and EFS responses. This study confirms the inhibitory effects of root extract of P. spinosa on rat ileum contraction. However, the root extract was not more effective than the aerial part extract. Therefore, the aerial parts extract of P. spinosa could be used as a suitable substitute for the root extract.