AIM

To observe the effect of Fructus Psoraleae on motility of isolated gallbladder muscle strips of guinea pigs and its mechanism.

METHODS

Guinea pigs were hit to lose consciousness and the whole gallbladder was removed quickly. Two or three smooth muscle strips (8 mm x 3 mm) were cut along a longitudinal direction. The mucosa was gently removed. Every longitudinal muscle strip was suspended in a tissue chamber which was continuously perfused with 5 mL Krebs solution (37 degrees of C), pH 7.4, and aerated with 950 mL/L O2 and 50 mL/L CO2. The isometric response was recorded with an ink-writing recorder. After 2 h equilibration under 1 g-load, 50 microL Fructus Psoraleae (10, 20, 70, 200, 700, 1000 g/L) was added cumulatively into the tissue chamber in turn every 2 min to observe their effects on gallbladder muscle strips (cumulating final concentration of Fructus Psoraleae was 0.1, 0.3, 1.0, 3.0, 10.0, 20.0 g/L). The antagonists, including 4-DAMP, benzhydramine, hexamethonium, phentolamine, verapamil and idomethine were given 2 min before Fructus Psoraleae respectively to investigate the mechanisms involved.

RESULTS

Fructus Psoraleae dose-dependently increased the resting tension (r = 0.992, P < 0.001), decreased the mean contractile amplitude (r = 0.970, P < 0.001) and meanwhile increased the contractile frequency of the gallbladder muscle strip in vitro (r = 0.965, P < 0.001). The exciting action of Fructus Psoraleae on the resting tension could be partially blocked by 4-DAMP (the resting tension decreased from 1.37 +/- 0.41 to 0.70 +/- 0.35, P < 0.001), benzhydramine (from 1.37 +/- 0.41 to 0.45 +/- 0.38, P < 0.001), hexamethonium (from 1.37 +/- 0.41 to 0.94 +/- 0.23, P < 0.05), phentolamine ( from 1.37 +/- 0.41 to 0.89 +/- 0.22, P < 0.01) and verapamil (from 1.37 +/- 0.41 to 0.94 +/- 0.26, P < 0.05). But the above antagonists had no significant effect on the action of Fructus Psoraleae-induced mean contractile amplitude (P > 0.05). Moreover, the increase of the contractile frequency due to Fructus Psoraleae was inhibited by 4-DAMP (decreased from 8.3 +/- 1.2 to 6.8 +/- 0.5, P < 0.01) and hexamethonium (from 8.3 +/- 1.2 to 7.0 +/- 0.9, P < 0.05). Idomethine had no significant effect on the Fructus Psoraleae-induced responses (P > 0.05).

CONCLUSION

Fructus Psoraleae enhances the motility of isolated gallbladder muscle strips from guinea pigs, in a dose-dependent manner. The effect of Fructus Psoraleae is partly related to M3, N receptor, alpha receptor, H1 receptor, Ca2+ channel, but not related to prostaglandin.