| Autor: |
Seitz, Ulrike, Ameri, Angela, Pelzer, Helmut, Gleitz, Johannes, Peters, Thies |
| Zdroj: |
Planta Medica; August 1997, Vol. 63 Issue: 4 p303-306, 4p |
| Abstrakt: |
Kava pyrones are the pharmacologically active compounds of PIPER METHYSTICUM Forst. In the present study, the effect of the synthetic kava pyrone ()-kavain was investigated on evoked contractile activity of isolated guinea-pig ileum. ()-Kavain (1 M-1 mM) dose-dependently reduced contractions of ileum evoked by carbachol (10 M), by BAY K 8644 (0.3 M), or by substance P (0.05 M). ()-Kavain also inhibited the contractile responses induced by raising the extracellular K + concentration from 4 to 20 mM and by blocking the K + channel by barium chloride (1 mM) or 4-aminopyridine (0.3 mM). After preincubation with 1 M nifedipine, carbachol (1 M) evoked 18.2 14.3% of contraction at control (i.e. prior pre-incubation with nifedipine). This remaining response was completely abolished by high concentrations of ()-kavain (400 M). After treatment of the longitudinal ileum strips with pertussis toxin (PTX), carbachol (1 M) evoked 27.0 6.2% of the control response in untreated ileum. These contractions were also blocked by ()-kavain (400 M). However, ()-kavain had no effect on the caffeine-induced (20 mM) contractions of ileum strips, which were permeabilized with digitonin or ?-escin. Moreover, it failed to affect Ca 2+-evoked contractions of skinned muscles. These results suggest that the kava pyrone ()-kavian may act in a nonspecific musculotropic way on the smooth muscle membrane. |
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