RESUMEN
Hydroalcoholic extract of Pycnocycla spinosa is a relaxant of rat ileum and inhibits diarrhea in mice. As P. spinosa extract has spasmolytic activity on ileum, it could also affect other smooth muscles like bladder. Therefore, the aim of this study was to determine the effect of P. spinosa extract on rat bladder contraction. In an in vitro study, the effects of P. spinosa extract, nifedipine and propantheline were tested on isolated rat bladder contractions induced by acetylcholine [ACh, 10 M] and KC1 [80 mM]. P. spinosa extract, concentration-dependently, inhibited the bladder contractions induced by ACh with an IC50 of 265 +/- 28 micro g/ml, and KC1 with an IC50 of 518 +/- 86 micro g/ml. The muscarinic cholinoceptor antagonist, propantheline, inhibited the response of ACh without affecting KC1 response. Nifedipine, on the other hand, abolished the KC1 response, while partially inhibiting the ACh contraction in rat bladder. The antispasmodic effect of P. spinosa extract on bladder was observed at higher concentrations as compared to that of ileum. Therefore, it is unlikely that P. spinosa extract at anti-diarrheal doses affect the normal bladder emptying function