Antispasmodic Effect of Piper nigrum Fruit Hot Water Extract on Rat Ileum

The aim of this study was to investigate the effect of black pepper fruit hot water extract (BPE) on rat ileum contractility and the mechanism(s) of its action. The extract was prepared by adding black pepper powder to boiling distilled water followed by evaporated the solvent. Ileum was dissected from male adult rat (Wistar) and in Tyrode solution the tissue contractions were recorded by an isotonic transducer under 1 g tension. The cumulative concentrations of the BPE (0.0625-1 mg mL(-1)) reduced the ileum contractions induced by KCl (60 mM) or carbachol (10 microM) concentration dependently (p<0.001). In Ca2+-free Tyrode solution with high potassium (60 mM), BPE, (0.0625-1 mg mL(-1)) attenuated the contractions induced by cumulative concentrations of CaCl2 (0.225-2.7 mM) concentration dependently (ANOVA, p<0.05). The incubation of the tissue preparation (20 or 30 min) with L-NAME (100 microM), naloxone (1 microM) or propranolol (1 microM) did not reduce the extract antispasmodic effect on KCl-induced ileum contraction. The extract spasmolytic effect was attenuated neither by glibenclamide (10 microM) nor by tetraethylammonium (1 mM). Present results suggest that the spasmolytic effect of the extract on rat ileum was possibly mediated via Ca2+ influx.