Quantitative and Fingerprint of Ilex pubescens Slices / 中国实验方剂学杂志

Objective:To establish HPLC-UV fingerprints of Ilex pubescens pieces,and simultaneously determine two components in 46 batches of I. pubescens in pieces of I. pubescens saponin A1 and B1,in order to provide a reference for the quality standard of I. pubescens slices. Method:Methanol was used to extract the I. pubescens saponin samples,and the extracts were measured by HPLC-UV with the absorption wavelength at 210 nm. Kromasil C18 column (4.6 mm×250 mm,5 μm) was used for determining the extracts at a flow rate of 1.0 mL·min-1. The mobile phase condition was acetonitrile-0.1% phosphoric acid aqueous solution with gradient mode. The chromatographic fingerprint similarity evaluation system of traditional Chinese medicine (2012 edition) was used to analyze I. pubescens fingerprints. SPSS 20.0 software was used to cluster the peak area of common peaks. Principal component analysis was performed to reduce the dimension of common peaks. Result:There were great differences between the root and stem parts in I. pubescens fingerprints. The fingerprints of roots and stems of I. pubescens were established respectively,cluster results assorted the roots of I. pubescens into three categories andthe branches of I. pubescens into two categories. The integrity and difference of I. pubescens decoction pieces from different parts and places of origin were compared,and the principal component analysis was performed to screen out the common components that played a decisive role in fingerprint of I. pubescens pieces. And the common peaks were determined. The content of saponin A1 and saponin B1 in Radix I. pubescens were determined. Conclusion:The established I. pubescens fingerprints and content determination methods are simple and suitable. Cluster analysis and principal component analysis are used to screen out the key components of quality control of I. pubescens. The results can provide references for quality control of I. pubescens.

Leak subtraction analysis of Axon patch clamp system / 中国应用生理学杂志

<p><b>AIM AND METHODS</b>Using blind whole-cell recording techniques on rat hippocampal slices, the function and mechanisms of several leak subtraction methods of Axon patch clamp system (Axopatch amplifier and pClamp software) were analyzed. That how to select and use scaled P/N leak subtraction, patch clamp amplifier leak subtraction and Clampfit leak subtraction were emphasized in our present study.</p><p><b>RESULTS</b>The noise induced by scaled P/N leak subtraction of Clampex soft ware was smaller than that of P/N leak subtraction. Axon patch clamp amplifier leak subtraction could subtract the leak current produced by single depolarizing pulse but not the leak current produced by a series of different step depolarizing pulses. Due to its assumption that leak current would be produced if only potential difference arises across membrane, Clampfit leak subtraction was not suitable to subtracting the steady-state leak current while recording voltage-gated channel currents.</p><p><b>CONCLUSION</b>P/N- and scaled P/N leak subtraction, but not Clampfit leak subtraction, cad be used to subtract steady-state leak current while recording voltage-gated channel currents.</p>

Difference in action sites between mecamylamine and hexamethonium on nicotinic receptors of sympathetic neurons / 生理学报

To compare the difference in action sites between mecamylamine (MEC) and hexamethonium (HEX) on nicotinic receptors of sympathetic neurons, we investigated the effects of MEC and HEX on the nicotine-induced currents in cultured superior cervical ganglion neurons by whole-cell patch clamp technique. The IC(50) of MEC and HEX for antagonizing the effect of 0.08 mmol/L nicotine was 0.0012 and 0.0095 mmol/L, respectively. Both MEC and HEX accelerated the desensitization of nicotinic receptors. Furthermore, by comparing their effects at holding potentials 30, 70 and 110 mV, it was indicated that their suppressing effect on the nicotine-induced currents was voltage-dependent. However, different from that of HEX, the inhibitory effect of MEC increased with administering the mixture of MEC and nicotine at intervals of 3 min, indicating a use-dependent effect of MEC. It is concluded that the action site of MEC on nicotinic receptors of sympathetic neurons is different from that of HEX.