Objectives Recent studies have described regional differences in the electrophysiology and pharmacology of ventric- ular myocardium in canine, feline, rat, guinea pig, and human hearts. This has been shown to be due t...Objectives Recent studies have described regional differences in the electrophysiology and pharmacology of ventric- ular myocardium in canine, feline, rat, guinea pig, and human hearts. This has been shown to be due to a smaller IKs and a lager sodium-calcium exchange current （INa-Ca） and late INa in M region （ deep subepicardial to midmyocardial）. Studies from our laboratory have found a new repolarization current-nonselective cation current （NSCCs） existing in rabbit fight ventricular myocytes. Methods We examined the characteristics of NSCCs in epicardial, M region, and endocardial cells isolated from the rabbit left ventricle with standard microelectrode and whole-cell patch-clamp tech- niques. The permeability to Na^＋ , K^＋ , Li^＋ , Cs^＋ but not to Cl^- indicating that it was a nonselective cation current. Gd^＋3 （0. 1 mmol/1） and La^3＋ （0. 1 retool/1 ） can block the current markedly. Results Further characterization of NSCCs was significantly smaller in M cells than in epicardial and endocardial cells. NSCCs current density was significantly smaller in M cells than in epicardial and endocardial cells. With repolarization to - 80 mV, INa current density was （ -0. 44 ±0. 05） PA/PF in endocardial cells, （ -0. 12 ±0. 05） PA/PF in M cells and （ - 0. 28 ±0. 07） PA/PF in epicardial cells ; and with repolarization to ＋ 30 mV, INa, current density was （ 1.09 ± 0. 29） PA/PF in endocardial cells, （0. 38±0. 09） PA/PF in M cells and （0. 91 ± 0. 32） PA/PF in epicardial cells. Conclusions Transmural dispersion of repolarization was due to the heterogeneity of NSCCs in rabbit left ventricle epicardial, endocardial myocytes and M cells. These findings may advance our understanding of the ionic basis for our understanding of factors contributing to the development of cardiac arrhythmias.展开更多
This contribution is not only intended to provide a fresh review for researches on static electrification, but also contains a sub- stantial amount of new material with a view of closing some gaps in the present state...This contribution is not only intended to provide a fresh review for researches on static electrification, but also contains a sub- stantial amount of new material with a view of closing some gaps in the present state of knowledge of oil streaming electrification. In this paper, the Electrostatic Charging Tendency (ECT) of fresh (unaged) and aged transformer oils were investigated in a spinning disk system. Static electrification measurement at different aging degrees was carried out under laboratory controlled conditions. Changes in static elec- trification were compared to some classical aging indexes (conductivity, dissipation factor, water content, resistivity, etc.). Fast, inexpensive and reliable laboratory testing procedures developed by American Society for Testing Materials (D 6802 and D 6181) were also used to monitor decay products as trace impurities. The obtained results show that static electrification currents increase with temperature, fluid mo- tion velocity, surface properties and the aging byproducts of the oil. The polarity, the amplitude and the time constant of the electrification currents are also affected. The results show that static electrification has relationship with thermal aging and is sensitive to turbidimetric and spectrophotometric measurements.展开更多
The prelimbic cortex(PL)plays a critical role in processing both the sensory and affective components of pain.However,the underlying molecular mechanisms remain poorly understood.In this study,we observed a reduction ...The prelimbic cortex(PL)plays a critical role in processing both the sensory and affective components of pain.However,the underlying molecular mechanisms remain poorly understood.In this study,we observed a reduction in hyperpolarization-activated cation current(Ih)in layer V pyramidal neurons of the contralateral PL in a mouse model of spared nerve injury(SNI).The expression of hyperpolarization-activated cyclic nucleotide-gated 2(HCN2)channels was also decreased in the contralateral PL.Conversely,microinjection of fisetin,a partial agonist of HCN2,produced both analgesic and anxiolytic effects.Additionally,we found that cyclin-dependent kinase 5(CDK5)was activated in the contralateral PL,where it formed a complex with HCN2 and phosphorylated its C-terminus.Knockdown of CDK5 restored HCN2 expression and alleviated both pain hypersensitivity and anxiety-like behaviors.Collectively,these results indicate that CDK5-mediated dysfunction of HCN2 in the PL underlies nerve injury-induced mechanical hypersensitivity and anxiety.展开更多
文摘Objectives Recent studies have described regional differences in the electrophysiology and pharmacology of ventric- ular myocardium in canine, feline, rat, guinea pig, and human hearts. This has been shown to be due to a smaller IKs and a lager sodium-calcium exchange current （INa-Ca） and late INa in M region （ deep subepicardial to midmyocardial）. Studies from our laboratory have found a new repolarization current-nonselective cation current （NSCCs） existing in rabbit fight ventricular myocytes. Methods We examined the characteristics of NSCCs in epicardial, M region, and endocardial cells isolated from the rabbit left ventricle with standard microelectrode and whole-cell patch-clamp tech- niques. The permeability to Na^＋ , K^＋ , Li^＋ , Cs^＋ but not to Cl^- indicating that it was a nonselective cation current. Gd^＋3 （0. 1 mmol/1） and La^3＋ （0. 1 retool/1 ） can block the current markedly. Results Further characterization of NSCCs was significantly smaller in M cells than in epicardial and endocardial cells. NSCCs current density was significantly smaller in M cells than in epicardial and endocardial cells. With repolarization to - 80 mV, INa current density was （ -0. 44 ±0. 05） PA/PF in endocardial cells, （ -0. 12 ±0. 05） PA/PF in M cells and （ - 0. 28 ±0. 07） PA/PF in epicardial cells ; and with repolarization to ＋ 30 mV, INa, current density was （ 1.09 ± 0. 29） PA/PF in endocardial cells, （0. 38±0. 09） PA/PF in M cells and （0. 91 ± 0. 32） PA/PF in epicardial cells. Conclusions Transmural dispersion of repolarization was due to the heterogeneity of NSCCs in rabbit left ventricle epicardial, endocardial myocytes and M cells. These findings may advance our understanding of the ionic basis for our understanding of factors contributing to the development of cardiac arrhythmias.
文摘This contribution is not only intended to provide a fresh review for researches on static electrification, but also contains a sub- stantial amount of new material with a view of closing some gaps in the present state of knowledge of oil streaming electrification. In this paper, the Electrostatic Charging Tendency (ECT) of fresh (unaged) and aged transformer oils were investigated in a spinning disk system. Static electrification measurement at different aging degrees was carried out under laboratory controlled conditions. Changes in static elec- trification were compared to some classical aging indexes (conductivity, dissipation factor, water content, resistivity, etc.). Fast, inexpensive and reliable laboratory testing procedures developed by American Society for Testing Materials (D 6802 and D 6181) were also used to monitor decay products as trace impurities. The obtained results show that static electrification currents increase with temperature, fluid mo- tion velocity, surface properties and the aging byproducts of the oil. The polarity, the amplitude and the time constant of the electrification currents are also affected. The results show that static electrification has relationship with thermal aging and is sensitive to turbidimetric and spectrophotometric measurements.
基金supported by the National Natural Science Foundation of China(32030052,W2411014 to Yun Wang,32271190 and 31972905 to Ying Zhang)the STI 2030 Major Project of the Ministry of Science and Technology of China(2021ZD0203204)the Beijing Natural Science Foundation(QY23067).
文摘The prelimbic cortex(PL)plays a critical role in processing both the sensory and affective components of pain.However,the underlying molecular mechanisms remain poorly understood.In this study,we observed a reduction in hyperpolarization-activated cation current(Ih)in layer V pyramidal neurons of the contralateral PL in a mouse model of spared nerve injury(SNI).The expression of hyperpolarization-activated cyclic nucleotide-gated 2(HCN2)channels was also decreased in the contralateral PL.Conversely,microinjection of fisetin,a partial agonist of HCN2,produced both analgesic and anxiolytic effects.Additionally,we found that cyclin-dependent kinase 5(CDK5)was activated in the contralateral PL,where it formed a complex with HCN2 and phosphorylated its C-terminus.Knockdown of CDK5 restored HCN2 expression and alleviated both pain hypersensitivity and anxiety-like behaviors.Collectively,these results indicate that CDK5-mediated dysfunction of HCN2 in the PL underlies nerve injury-induced mechanical hypersensitivity and anxiety.
