Effect of rhubarb on contractile response of gallbladder smooth muscle strips isolated from guinea pigs

AIM: To investigate the effect of rhubarb on contractile response of isolated gallbladder muscle strips from guinea pigs and its mechanism.METHODS: Guinea pigs were killed to remove the whole gallbladder. Two or three smooth muscle strips (8 mm×3mm) were cut along the longitudinal direction. The mucosa on each strip was carefully removed. Each longitudinal muscle strip was suspended in a tissue chamber containing 5 mL Krebs solution (37 ℃), bubbled continuously with 950 mL/L O2 and 50 mL/L CO2. The resting tension (g), mean contractile amplitude (mm),and contractile frequency (waves/min) were simultaneously recorded on recorders. After 2-h equilibration, rhubarb (10, 20, 70, 200, 700, 1 000 g/L) was added cumulatively to the tissue chamber in turns every 2 min to observe their effects on gallbladder.Antagonists were given 3 min before administration of rhubarb to investigate the possible mechanism.RESULTS: Rhubarb increased the resting tension (from 0 to 0.40±0.02, P＜0.001), and decreased the mean contractile amplitude (from 5.22±0.71 to 2.73±0.41,P＜0.001). It also increased the contractile frequency of the gallbladder muscle strips in guinea pigs (from 4.09±0.46to 6.08±0.35, P＜0.001). The stimulation of rhubarb on the resting tension decreased from 3.98±0.22 to 1.58±0.12by atropine (P＜0.001), from3.98±0.22 to 2.09±0.19 by verapamil (P＜0.001) and from 3.98±0.22 to 2.67±0.43by phentolamine (P＜0.005). But the effect was not inhibited by hexamethonium (P＞0.05). In addition, the action of mean amplitude and frequency was not inhibited by the above antagonists.CONCLUSION: Rhubarb can stimulate the motility of isolated gallbladder muscle strips from guinea pigs. The stimulation of rhubarb might be relevant with M receptor,Ca2+ channel and α receptor partly.

Effect of Fructus Psoraleae on motility of gallbladder isolated smooth muscle strips from guinea pigs

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×3mm） 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℃）, pH 7.4, and aerated with 950 mL/L 02 and 50 mL/L CO2. The isometric response was recorded with an ink-writing recorder. After 2 h equilibration under i g-load, 50 μL Fructus Psoraleae （10, 20, 70, 200, 700, 1000 g/L） was added cumulatively into the tissue chamber in turn every 2 rain 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, α receptor, H1 receptor, Ca^2＋ channel, but not related to prostaglandin.