Characteristics of Transient Outward Potassium Channel Exposed to 3 mT Static Magnetic Field

Acutely isolated mouse hippocampal CA3 pyramidal neurons were exposed to 3 mT static magnetic field,and the characteristics of transient outward K+ channel were studied using the whole-cell patch-clamp technique.The experiment revealed that the amplitude of transient outward potassium channel current was reduced.The maximum activated current densities of control group and exposure group were 163.62±20.68 pA/pF and 98.74±16.57 pA/pF(n=12,P<0.01) respectively.The static magnetic field exposure affected the activation and inactivation process of transient outward potassium channel current.Due to the magnetic field exposure,the half-activation voltage of the activation curves changed from 5.59±1.96 mV to 27.87±7.24 mV(n=12,P<0.05) ,and the slope factor changed from 19.43±2.11 mV to 25.87±4.22 mV(n=12,P<0.05) .The half-inactivation voltage of the inactivation curves also changed from-56.09±0.89 mV to-57.16±1.10 mV(n=12,P>0.05) and the slope factor of the inactivation curves from 8.69±0.80 mV to 10.87±1.02 mV(n=12,P<0.05) .The results show that the static magnetic field can change the characteristics of transient outward K+ channel,and affect the physiological functions of neurons.

Effect of acupuncture combined with Xijing Tongmai decoction on the sustained expression of transient outward potassium channel related protein in rats with myocardial infarction

Objective:To observe the sustained expression of transient outward potassium channel related proteins at the end of the treatment and 30 days after the end of the treatment in rats,and to explore the sustained curative effect and mechanism of acupuncture combined with Xijingtongmai decoction in rats with myocardial infarction.Methods:Twenty of 130 male SD rats were random extracted as the control group,and the rest were used to establish myocardial infarction by fed with high-fat diet and then injected with isoproterenol.According to ECG,80 rats were successfully established.Then they were randomly divided into model group,acupuncture combined with Chinese medicine group,acupuncture group and Western medicine group.The content of bFGF protein was measured by ELISA.The protein contents of Kv1.4,Kv4.2,Kv4.3 and KChIP2 were measured by Western blot.Results:At the end of treatment,compared with the model group,the protein contents of Kv1.4,Kv4.2,Kv4.3,KChIP2 and bFGF in each treatment group increased,and the increase was most significant in the acupuncture combined with Chinese medicine group(P<0.05).At the end of treatment,compared with the model group,the protein contents of Kv1.4,Kv4.2,Kv4.3,KChIP2 and bFGF in each treatment group increased,and the increase was most significant in the acupuncture combined with Chinese medicine group(P<0.05).Compared with the treatment group at the end of treatment,the expression of Kv1.4,Kv4.2,Kv4.3,KChIP2 and bFGF protein in each treatment group 30 days after the end of treatment decreased slightly(P<0.05),but still higher than that of the model group at this time(P<0.05).The combination of acupuncture and Chinese medicine group decreased the least of them(P<0.05).Conclusion:The results showed that acupuncture combined with xijingtongmai decoction had a sustained good effect.Its sustained action mechanism may be achieved by continuously increasing the protein content of Kv1.4,Kv4.2,Kv4.3,KChIP2 and bFGF through transient outward potassium channel.

Acetylcholine modulates transient outward potassium channel in acutely isolated cerebral cortical neurons of rats

BACKGROUND： The neuronal transient outward potassium channel has been shown to be highly associated with acetylcholine. However, the influence of acetylcholine on the transient outward potassium current in cerebral cortical neurons remains poorly understood. OBJECTIVE： To investigate acetylcholine modulation on transient outward potassium current in rat parietal cortical neurons using the whole-cell patch-clamp technique. DESIGN, TIME AND SETTING： A neuroelectrophysiology study was performed at the Department of Physiology, Harbin Medical University between January 2005 and January 2006. MATERIALS： Wistar rats were provided by the Animal Research Center, the Second Hospital of Harbin Medical University; PC-IIC patch-clamp amplifier and IBBClamp data collection analysis system were provided by Huazhong University for Science and Technology, Wuhan, China; PP-83 microelectrode puller was purchased from Narrishage, Japan. METHODS： The parietal somatosensory cortical neurons were acutely dissociated, and the modulation of acetylcholine （0.1, 1, 10, 100 μmol/L） on transient outward potassium channel was recorded using the whole-cell patch-clamp technique. MAIN OUTCOME MEASURES： Influence of acetylcholine on transient outward potassium current, potassium channel activation, and inactivation. RESULTS： The inhibitory effect of acetylcholine on transient outward potassium current was dose- and voltage-dependent （P 〈 0.01）. Acetylcholine was found to significantly affect the activation process of transient outward potassium current, i.e., the activation curve of transient outward potassium current was left-shifted, while the inactivation curve was shifted to hyperpolarization. Acetylcholine significantly prolonged the time constant of recovery from inactivation of transient outward potassium current （P 〈 0.01）. CONCLUSION： These results suggest that acetylcholine inhibits transient outward potassium current by regulating activation and inactivation processes of the transient outward potassium channel.