Objective To investigate the effect of different duration skeletal muscle denervation on acetylcholine receptor activity in rats.Methods Fourteen Balb/c mice weighing 18-22 g were used in this study.The denervation model was established by excising sciatic nerve.Two rats were chosen before(T0 ) and at days 1,4,7,14,21 and 28 after excising sciatic nerve (T1～6),and flexor digitorum brevis of the hindfoot was acutely isolated Skeletal muscle cells were isolated ( five cells in each rat),the acetylcholine currents were recorded using whole-cell patch-clamo technique.Extracellular fluid containing 30 μmol/L acetylcholine was first applied to skeletal muscle cells for 10 s,acetylcholine currents (11)were recorded,then the ceils were washed out using extracellularfluid.Skeletal muscle cells were balanced using extracellular fluid containing 0,0.1,1,10,30,100,1000,3000,or 10 000 nmol/L atracurium for 3 min respectively,then perfused using extracellular fluid containing 30 μmol/L acetylcholine and differents concentrations of atracurium mentioned above for 10 s respectively,and acetylcholine currents were recorded,then the cells were washed out,and 30 μmol/L acetylcholine was perfused again and currents(I2 ) were recorded.The mean value of I1 and I2 was taken as control current,and inhibitory percentage of control current was calculated,and the inhibition concentrations for the half-maximal response (IC50) of atracurium were determined by nonlinear regression analysis.Results Compared with T0,IC50 significantly increased at T1～6 ( P ＜ 0.05).IC50 was increased gradually at T1～3 ( P ＜ 0.05).Compared with T3,IC50 was decreased at T4～6 ( P ＜ 0.05).IC50 was decreased gradually at T4～6 ( P ＜ 0.05 ).Conclusion Skeletal muscle denervation can inhibite acetylcholine receptor activity,which is relate to the denervation time.

BACKGROUND:Tissue-engineered transplantation technique has become an ideal therapeutic regimen for degenerative disc diseases through reconstituting the biological functions of the degenerated intervertebral discs.
OBJECTIVE:To construct a novel tissue-engineered annular fibrosus scaffold.
METHODS:Konjac glucomannan, nano-hydroxyapatite and colagen were used to fabricate a new tissue-engineered annular fibrosus scaffold by wet spinning, chemical crosslinking, and freeze drying methods. Afterwards, X-ray diffraction and Fourier transform infrared spectrometer were used to analyze the scaffold qualitative components, physico-chemical property, biomechanical performance and cytocompatibility.
RESULTS AND CONCLUSION:The bionic scaffold had a three-dimensional porous structure, with the average pore size of (425.8±47.3) μm, the average porosity of (73.4±5.6)%, and the water absorption of (718.6±24.3)%. In addition, the compressive strength of the scaffold was similar with that of the natural annular fibrosus. More importantly, the scaffold had good biocompatibility without cytotoxicity. These results show that the tissue-engineered annular fibrosus scaffold constructed by konjac glucomannan, nano-hydroxyapatite and colagen has proper three-dimensional porous structure, biocompatibility, porosity, water absorption and biomechanical strength.