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...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.展开更多
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 r...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.展开更多
Objective： To determine the effect of different concentrations of Radix Saposhnikoviae （RS） on the contraction of smooth muscle strips and the Ca2＋ mobilization of cultured smooth muscle ceils of rat colon and its...Objective： To determine the effect of different concentrations of Radix Saposhnikoviae （RS） on the contraction of smooth muscle strips and the Ca2＋ mobilization of cultured smooth muscle ceils of rat colon and its possible mechanism of action. Methods： Strips of rat colon longitudinal muscle were prepared and smooth muscle cells from rat colon were isolated and cultured. In the experiments, in vitro muscle strips were suspended in an organ bath and the contraction of the strips was recorded. In the cell- experiments, intracellular Ca2＋ was assessed using fluorescent intensity （FI） of smooth muscle cells loaded with Fluo-4/AM, measured with a laser scanning confocal microscope and related software. Results： In the in vitro experiment, RS （0.02, 0.2, 2, 20 g/L） inhibited contraction of muscle strips in a concentration-dependent manner, and this inhibition was significant for the three higher RS concentrations （P 〈 0.01） for both Peak （the maximal contraction amplitude） and Area （the area under curves）. Similarly, RS inhibited Ach-induced contraction. In these experiments the inhibition of the Peak values in the RS 2 and 20 g/L groups was significant （P 〈 0.01）, as was the inhibition of the Area values in all RS groups （P 〈 0.05）. Naloxone and propranolol did not significantly affect the inhibitory effect of RS on smooth muscle contractility, while phentolamine significantly reduced the inhibitory effect （P 〈 0.01）. In experiments using primary smooth muscle cell cultures in Ca2＋ - containing buffer, the post-treatment fluorescence of cells in the RS 0.2, 2 and 20 g/L groups differed significantly from pre-treatment values （P 〈 0.05）, and the percent inhibition of fluorescence in the RS 2 g/L and 20 g/L groups was significant （P 〈 0.01）. However, in Ca2＋-free buffer, FS had no significant effect on cell fluorescence. Conclusion： RS inhibited both the spontaneous and Ach-stimulated contraction of rat colonic smooth muscle strips. This RS effect appeared to involve α -adrenoceptors, but not β -adrenoceptors or opioid receptors. In cultured primary smooth muscle cells, RS reduced the mobilization of Ca2＋ from extracellular sources, but may had no effect on the release of Ca2＋ from sarcoplasmic reticulum and endoplasmic reticulum.展开更多
Background Diabetic gastroparesis is a disabling condition with no consistently effective treatment. In normal animals, both ghrelin and its synthetic peptide, growth hormone releasing peptide 6 （GHRP-6）, increase g...Background Diabetic gastroparesis is a disabling condition with no consistently effective treatment. In normal animals, both ghrelin and its synthetic peptide, growth hormone releasing peptide 6 （GHRP-6）, increase gastric emptying. Thus, we investigated the potential therapeutic significance of ghrelin and GHRP-6 in diabetic guinea pigs with gastric motility disorders. Methods A diabetic guinea pig model was produced by intraperitoneal （i.p.） injection of streptozotocin （STZ, 280 mg/kg）. Diabetic guinea pigs were injected i.p. with ghrelin or GHRP-6 （10-100 μg/kg）, and the effects on gastric emptying were measured after intragastric application of phenol red. The effect of atropine or a growth hormone secretagogue receptor （GHS-R） antagonist, D-Lys^3-GHRP-6, on the gastroprokinetic effects of ghrelin or GHRP-6 （100 μg/kg） was also investigated. Further, the in vitro effects of ghrelin or GHRP-6 （0.01-10 μmol/L） on spontaneous or carbachol-induced contractile amplitude in gastric fundic circular strips taken from diabetic guinea pigs were examined. Growth hormone secretagogue receptor transcripts in the fundic strips of diabetic guinea pigs were detected by reverse transcriptase polymerase chain reaction （RT-PCR）. Results We established a guinea pig model of delayed gastric emptying. Ghrelin （20, 50, or 100 μg/kg） and GHRP-6 （20, 50, or 100 μg/kg） accelerated gastric emptying in diabetic guinea pigs with gastroparesis （n=6, P 〈0.05）. In the presence of atropine, which delayed gastric emptying, ghrelin and GHRP-6 （100 μg/kg） failed to accelerate gastric emptying （n=6, P 〈0.05）. D-Lys^3-GHRP-6 also delayed gastric emptying induced by the GHS-R agonist （n=6, P 〈0.05）. Ghrelin and GHRP-6 increased the carbachol-induced contractile amplitude in gastric fundic strips taken from diabetic guinea pigs （n=6, P〈0.05）. RT-PCR confirmed the presence of GHS-R mRNA in the strip preparations. Conclusions Ghrelin and GHRP-6 increased gastric emptying in diabetic guinea pigs with gastroparesis, potentially, by activating the peripheral cholinergic pathways in the enteric nervous system.展开更多
基金Supported by the Key Laboratory of Pre-clinical Research for Chinese HerbsNew Drugs of Gansu Province and The Natural Scientific Foundation of Gansu Province, No. zs021-A25-059-Y
文摘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.
基金Supported by Key Laboratory of Pre-clinical Study for New Drugs of Gansu Province and the Natural Science Foundation of Gansu Province, No.ZS021-A25-059-Y
文摘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.
基金Supported by the TCM Leader Talent Funds on Health Revitalization Project of Jiangsu Province,Health Financial Plan of Jiangsu Province,No.2007/158
文摘Objective： To determine the effect of different concentrations of Radix Saposhnikoviae （RS） on the contraction of smooth muscle strips and the Ca2＋ mobilization of cultured smooth muscle ceils of rat colon and its possible mechanism of action. Methods： Strips of rat colon longitudinal muscle were prepared and smooth muscle cells from rat colon were isolated and cultured. In the experiments, in vitro muscle strips were suspended in an organ bath and the contraction of the strips was recorded. In the cell- experiments, intracellular Ca2＋ was assessed using fluorescent intensity （FI） of smooth muscle cells loaded with Fluo-4/AM, measured with a laser scanning confocal microscope and related software. Results： In the in vitro experiment, RS （0.02, 0.2, 2, 20 g/L） inhibited contraction of muscle strips in a concentration-dependent manner, and this inhibition was significant for the three higher RS concentrations （P 〈 0.01） for both Peak （the maximal contraction amplitude） and Area （the area under curves）. Similarly, RS inhibited Ach-induced contraction. In these experiments the inhibition of the Peak values in the RS 2 and 20 g/L groups was significant （P 〈 0.01）, as was the inhibition of the Area values in all RS groups （P 〈 0.05）. Naloxone and propranolol did not significantly affect the inhibitory effect of RS on smooth muscle contractility, while phentolamine significantly reduced the inhibitory effect （P 〈 0.01）. In experiments using primary smooth muscle cell cultures in Ca2＋ - containing buffer, the post-treatment fluorescence of cells in the RS 0.2, 2 and 20 g/L groups differed significantly from pre-treatment values （P 〈 0.05）, and the percent inhibition of fluorescence in the RS 2 g/L and 20 g/L groups was significant （P 〈 0.01）. However, in Ca2＋-free buffer, FS had no significant effect on cell fluorescence. Conclusion： RS inhibited both the spontaneous and Ach-stimulated contraction of rat colonic smooth muscle strips. This RS effect appeared to involve α -adrenoceptors, but not β -adrenoceptors or opioid receptors. In cultured primary smooth muscle cells, RS reduced the mobilization of Ca2＋ from extracellular sources, but may had no effect on the release of Ca2＋ from sarcoplasmic reticulum and endoplasmic reticulum.
基金This study was supported by a grant from National Natural Science Foundation of China （No. 30400429）.
文摘Background Diabetic gastroparesis is a disabling condition with no consistently effective treatment. In normal animals, both ghrelin and its synthetic peptide, growth hormone releasing peptide 6 （GHRP-6）, increase gastric emptying. Thus, we investigated the potential therapeutic significance of ghrelin and GHRP-6 in diabetic guinea pigs with gastric motility disorders. Methods A diabetic guinea pig model was produced by intraperitoneal （i.p.） injection of streptozotocin （STZ, 280 mg/kg）. Diabetic guinea pigs were injected i.p. with ghrelin or GHRP-6 （10-100 μg/kg）, and the effects on gastric emptying were measured after intragastric application of phenol red. The effect of atropine or a growth hormone secretagogue receptor （GHS-R） antagonist, D-Lys^3-GHRP-6, on the gastroprokinetic effects of ghrelin or GHRP-6 （100 μg/kg） was also investigated. Further, the in vitro effects of ghrelin or GHRP-6 （0.01-10 μmol/L） on spontaneous or carbachol-induced contractile amplitude in gastric fundic circular strips taken from diabetic guinea pigs were examined. Growth hormone secretagogue receptor transcripts in the fundic strips of diabetic guinea pigs were detected by reverse transcriptase polymerase chain reaction （RT-PCR）. Results We established a guinea pig model of delayed gastric emptying. Ghrelin （20, 50, or 100 μg/kg） and GHRP-6 （20, 50, or 100 μg/kg） accelerated gastric emptying in diabetic guinea pigs with gastroparesis （n=6, P 〈0.05）. In the presence of atropine, which delayed gastric emptying, ghrelin and GHRP-6 （100 μg/kg） failed to accelerate gastric emptying （n=6, P 〈0.05）. D-Lys^3-GHRP-6 also delayed gastric emptying induced by the GHS-R agonist （n=6, P 〈0.05）. Ghrelin and GHRP-6 increased the carbachol-induced contractile amplitude in gastric fundic strips taken from diabetic guinea pigs （n=6, P〈0.05）. RT-PCR confirmed the presence of GHS-R mRNA in the strip preparations. Conclusions Ghrelin and GHRP-6 increased gastric emptying in diabetic guinea pigs with gastroparesis, potentially, by activating the peripheral cholinergic pathways in the enteric nervous system.
