Objective To investigate the effects of motilin on the voltage dependent potassium channel and L-type calcium channel currents in rat proximal colon smooth muscle cells (PCSM) and to explore its mechanism in increasing colonic motility.Methods PCSM were isolated by collagenase.The voltage dependent potassium channel transit outward current (IKA ) and delayed rectifier current (IKdr) and L-type calcium currents (ICa(L)) were measured by whole cell patch clamp technique.Groups were analyzed by paired t-test.Results There was no significant effect of motilin on IKA and IKdr.L-type calcium channel was dose-dependently activated by motilin from 0.5 × 105 mmol/L to 10.0 ×10-5 mmol/L.At 6 × 10-5 mmol/L motilin and under - 10,0 and 10 mV stimulating voltage,maximum current density increased by 154.61％,62.69％ and 21.02％ respectively and activation kinetics curve obviously left shifted.Half activation voltage decreased from (2.740±1.211) mV prior administration to ( - 25.290 ± 0.614) mV (t =8.534,P =0.007 ) and there was no significant difference in slope factor. Conclusions Motilin increases colonic smooth muscle contraction by promoting calcium influx. However the frequency of colonic smooth muscle contraction could not change with frequency of equilibrium potential and action potential of colonic smooth muscle.

AIM:To compare three different solvent extraction procedures affecting the extraction rate of polysaccharide from Schisandra chinensis (Turcz.). METHODS: We used single factor experiments, optimized the extraction process of polysaccharide from Schisandra chinensis (Turcz.) by alkali solution and ethanol-alkali solution, respectively, and contrasted the two methods with the water extraction method that had been reported, determined the extraction rate of polysaccharide by optimum condition of three kinds of solvent. RESULTS: These results showed that ethanol-alkali extraction procedure had the highest extraction rate, 1.12 times more than water extraction procedure and 1.06 times more than alkali extraction procedure. CONCLUSION: Ethanol-alkali extraction procedure is a high effective and stable for polysaccharide from Schisandra chinensis (Turcz.).

Aim To investigate the direct effects and mechanism of carvedilol on HERG channel stably expressing in human embryonic kidney-293(HEK293) cells.Methods Whole-cell patch-clamp technique was used to record HERG current and kinetic curves in single cells.Western blot methods were used to investigate the expression of HERG channel in different concentration of carvedilol.Result Carvedilol decreased HERG current in a concentration-dependent manner with an IC50 539.6 nmol?L-1,Hillslope-0.64.The time constants of onset of inactivation and deactivation were accelerated.Other kinetcs(activation,inactivation,recovery from inactivation)had no significant changes.Based on western result,carvedilol had no effect on the generation and trafficking of HERG protein.Conclusion Carvedilol inhibits the transfected HERG channels by influencing the open state which is the probable anti-arrhythmic mechanism.There is no relationship between carvedilol and HERG channel expression.