Objective Allocryptopine （ALL） is an effective alkaloid of Corydalis decumbens （Thunb.） Pers. Papaveraceae and has proved to be an- ti-arrhythmic. The purpose of our study is to investigate the effects of ALL on t...Objective Allocryptopine （ALL） is an effective alkaloid of Corydalis decumbens （Thunb.） Pers. Papaveraceae and has proved to be an- ti-arrhythmic. The purpose of our study is to investigate the effects of ALL on transmural repolarizing ionic ingredients of outward potassium current （Ito） and slow delayed rectifier potassium current （IKs）. Methods The monophasic action potential （MAP） technique was used to record the MAP duration of the epicardium （Epi）, myocardium （M） and endocardium （Endo） of the rabbit heart and the whole cell patch clamp was used to record/to and IKs in cardiomyocytes of Epi, M and Endo layers that were isolated from rabbit ventricles. Results The effects of ALL on MAP of Epi, M and Endo layers were disequilibrium. ALL could effectively reduce the transmural dispersion of repolarization （TDR） in rabbit transmural ventricular wall. ALL decreased the current densities of/to and IKs in a voltage and concentration dependent way and narrowed the repolarizing differences among three layers. The analysis of gating kinetics showed ALL accelerated the channel activation ofIto in M layers and partly inhibit the channel openings of/to in Epi, M and Endo cells. On the other hand, ALL mainly slowed channel deactivation of IKs channel in Epi and Endo layers without affecting its activation. Conclusions Our study gives partially explanation about the mechanisms of tmnsmural inhibition of/to and IKs channels by ALL in rabbit myocardium. These findings provide novel perspective regarding the anti-arrhythmogenesis application of ALL in clinical settings.展开更多
The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （H...The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （HASM）, by measuring tones and whole-cell patch clamp techniques, and the Kv activities and membrane potential （Em） were also detected. The results showed that phorbol 12-myristate 13-acetate （PMA）, a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group （P〈0.05）, and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. Kv activities of HASM cells were significantly inhibited by PMA, and the Em became more positive, as compared with the DMSO （a PMA menstruum）-treated group （P〈0.01）. This effect could be blocked by Ro31-8220 （P〈0.01 ）. It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced Kv activity. In passively sensitized HASM rings, this effect was more notable.展开更多
The effects of BTHP on Ca 2+ independent action potential and the two components of delayed rectifier potassium currents were studied in guinea pig single ventricular myocytes by using whole cell patch clamp tec...The effects of BTHP on Ca 2+ independent action potential and the two components of delayed rectifier potassium currents were studied in guinea pig single ventricular myocytes by using whole cell patch clamp technique. BTHP 30 μmol·L -1 significantly prolonged APD 90 from 143±16 ms to 184±21 ms ( P 【0.01, n=5) without affecting either the RP or APA, and the APD prolonging effects of BTHP were independent of extracellular Ca 2+ . BTHP inhibited both I kr (IC 50 =7 9 μmol·L -1 ) and I ks (IC 50 =22 4 μmol·L -1 ) in a concentration dependent fashion. The results demon strated that BTHP had no obvious selectivity for I kr and I ks .展开更多
Background Potassium (K +) channels are important in regulating cell membrane potential and excitability. Although bronchial myocytes from asthmatic rats show a significant reduction in voltage-dependent delayed rec...Background Potassium (K +) channels are important in regulating cell membrane potential and excitability. Although bronchial myocytes from asthmatic rats show a significant reduction in voltage-dependent delayed rectifier potassium channel (Kv) current density and higher excitability, the activity and expression of Kv in human bronchial smooth muscle cells (HBSMCs) have never been studied. The ob jective of this study was to investigate the effect of passive sensitization by asthmatic serum on the activity of Kv and the expression of Kv isoform Kv1.5 in HBSMCs.Methods HBSMCs were randomly divided into two groups: control group (containing 10% serum from nonatopic individuals) and sensitized group (containing 10% asthmatic serum), then cultured for 24 hours. Whole-cell patch clamp, immunofluorescence staining, reverse transcription-polymerase chain reaction and Western blot techniques were used to study the effect of passive sensitization on the activity of Kv and the expression of Kv1.5 in HBSMCs.Results The membrane potential in passively sensitized HBSMCs was significantly depolarized to -(26.7±5.2) mV compared with -(41.3±6.4) mV in the cont rol group (P<0.01). Passive sensitization caused a significant inhibition of Kv currents in HBSMCs, resulting in a downward shift in the current-voltage (Ⅰ-Ⅴ) relationship curve. At +50mV, the peak Kv current density of passively sensitized HBSMCs was significantly decreased from (54.6±8.7) picoamperes per picofarad ( pA/pF) to (32.1±7.1) pA/pF (P<0.01). The expression level of Kv1.5 mRNA in passively sensitized HBSMCs was significantly lower than that in the control group (0.76±0.07 vs 1.04±0.13, P<0.05). The expression of Kv1.5 protein of passively sensitized HBSMCs was also significantly reduced compared to that from the control group (984±168 vs 2200±380, P<0.05).Conclusions The activity and expression of Kv were all decreased in HBSMCs passively sensitized by asthmatic serum compared with nonsensitized cells. These changes might be involved in the mechanisms of formation and development of asthma.展开更多
Background：Stellate ganglion （SG） plays an important role in cardiovascular diseases.The electrical activity of SG neurons is involved in the regulation of the autonomic nervous system.The aim of this research was ...Background：Stellate ganglion （SG） plays an important role in cardiovascular diseases.The electrical activity of SG neurons is involved in the regulation of the autonomic nervous system.The aim of this research was to evaluate the effects offluvastatin on the electrophysiological characteristics of SG neurons in a rabbit model of myocardial ischemia （MI）.Methods：The MI model was induced by abdominal subcutaneous injections of isoproterenol in rabbits.Using whole-cell patch clamp technique,we studied the characteristic changes of ion channels and action potentials （APs） in isolated SG neurons in control group （n =20）,MI group （n =20） and fluvastatin pretreated group （fluvastatin group,n =20）,respectively.The protein expression of sodium channel in SG was determined by immunohistochemical analysis.Results：MI and the intervention of fluvastatin did not have significantly influence on the characteristics of delayed rectifier potassium channel currents.The maximal peak current density of sodium channel currents in SG neurons along with the characteristics of activation curves,inactivation curves,and recovery curves after inactivation were changed in the MI group.The peak current densities of control group,MI group,and fluvastatin group （n =10 in each group） were-71.77 ± 23.22 pA/pF,-126.75 ± 18.90 pA/pF,and-86.42 ± 28.30 pA/pF,respectively （F=4.862,P =0.008）.Fluvastatin can decrease the current amplitude which has been increased by MI.Moreover,fluvastatin induced the inactivation curves and post-inactive recovery curves moving to the position of the control group.But the expression of sodium channel-associated protein （Nav 1.7） had no significantly statistical difference among the three groups.The percentages of Nav 1.7 protein in control group,MI group,and fluvastatin group （n =5 in each group） were 21.49 ± 7.33%,28.53 ± 8.26%,and 21.64 ± 2.78%,respectively （F =1.495,P =0.275）.Moreover,MI reduced the electrical activity of AP and increased amplitude of AP,fluvastatin pretreatment could recover amplitude and electrical activity of AP.The probability of neurons induced continuous APs were 44.44%,14.29%,and 28.57% in control group,MI group,and fluvastatin group,respectively.Conclusions：Fluvastatin pretreatment can recover electrophysiology characteristics of ion channel and AP in SG neurons in a rabbit model of MI.It could be considered as potential method for treating coronary heart diseases.展开更多
文摘Objective Allocryptopine （ALL） is an effective alkaloid of Corydalis decumbens （Thunb.） Pers. Papaveraceae and has proved to be an- ti-arrhythmic. The purpose of our study is to investigate the effects of ALL on transmural repolarizing ionic ingredients of outward potassium current （Ito） and slow delayed rectifier potassium current （IKs）. Methods The monophasic action potential （MAP） technique was used to record the MAP duration of the epicardium （Epi）, myocardium （M） and endocardium （Endo） of the rabbit heart and the whole cell patch clamp was used to record/to and IKs in cardiomyocytes of Epi, M and Endo layers that were isolated from rabbit ventricles. Results The effects of ALL on MAP of Epi, M and Endo layers were disequilibrium. ALL could effectively reduce the transmural dispersion of repolarization （TDR） in rabbit transmural ventricular wall. ALL decreased the current densities of/to and IKs in a voltage and concentration dependent way and narrowed the repolarizing differences among three layers. The analysis of gating kinetics showed ALL accelerated the channel activation ofIto in M layers and partly inhibit the channel openings of/to in Epi, M and Endo cells. On the other hand, ALL mainly slowed channel deactivation of IKs channel in Epi and Endo layers without affecting its activation. Conclusions Our study gives partially explanation about the mechanisms of tmnsmural inhibition of/to and IKs channels by ALL in rabbit myocardium. These findings provide novel perspective regarding the anti-arrhythmogenesis application of ALL in clinical settings.
基金This project was supported by a grant from the National Natural Sciences Foundation of China (No. 30270583)
文摘The effects of protein kinase C （PKC） on the tension and the activity of voltage-dependent delayed rectifier potassium channel （K,,） were examined in normal and passively sensitized human airway smooth muscle （HASM）, by measuring tones and whole-cell patch clamp techniques, and the Kv activities and membrane potential （Em） were also detected. The results showed that phorbol 12-myristate 13-acetate （PMA）, a PKC activator, caused a concentration-dependent constriction in normal HASM rings. The constriction of the passively sensitized muscle in asthma serum group was significantly higher than that of the normal group （P〈0.05）, and the constrictions of both groups were completely abolished by PKC inhibitor Ro31-8220 and calcium channel inhibitor nifedipine. Kv activities of HASM cells were significantly inhibited by PMA, and the Em became more positive, as compared with the DMSO （a PMA menstruum）-treated group （P〈0.01）. This effect could be blocked by Ro31-8220 （P〈0.01 ）. It was concluded that activation of PKC could increase the tones of HASM, which might be related to the reduced Kv activity. In passively sensitized HASM rings, this effect was more notable.
文摘The effects of BTHP on Ca 2+ independent action potential and the two components of delayed rectifier potassium currents were studied in guinea pig single ventricular myocytes by using whole cell patch clamp technique. BTHP 30 μmol·L -1 significantly prolonged APD 90 from 143±16 ms to 184±21 ms ( P 【0.01, n=5) without affecting either the RP or APA, and the APD prolonging effects of BTHP were independent of extracellular Ca 2+ . BTHP inhibited both I kr (IC 50 =7 9 μmol·L -1 ) and I ks (IC 50 =22 4 μmol·L -1 ) in a concentration dependent fashion. The results demon strated that BTHP had no obvious selectivity for I kr and I ks .
基金ThisstudywassupportedbytheNationalNaturalScienceFoundationofChina (No 3 0 2 70 5 83 )
文摘Background Potassium (K +) channels are important in regulating cell membrane potential and excitability. Although bronchial myocytes from asthmatic rats show a significant reduction in voltage-dependent delayed rectifier potassium channel (Kv) current density and higher excitability, the activity and expression of Kv in human bronchial smooth muscle cells (HBSMCs) have never been studied. The ob jective of this study was to investigate the effect of passive sensitization by asthmatic serum on the activity of Kv and the expression of Kv isoform Kv1.5 in HBSMCs.Methods HBSMCs were randomly divided into two groups: control group (containing 10% serum from nonatopic individuals) and sensitized group (containing 10% asthmatic serum), then cultured for 24 hours. Whole-cell patch clamp, immunofluorescence staining, reverse transcription-polymerase chain reaction and Western blot techniques were used to study the effect of passive sensitization on the activity of Kv and the expression of Kv1.5 in HBSMCs.Results The membrane potential in passively sensitized HBSMCs was significantly depolarized to -(26.7±5.2) mV compared with -(41.3±6.4) mV in the cont rol group (P<0.01). Passive sensitization caused a significant inhibition of Kv currents in HBSMCs, resulting in a downward shift in the current-voltage (Ⅰ-Ⅴ) relationship curve. At +50mV, the peak Kv current density of passively sensitized HBSMCs was significantly decreased from (54.6±8.7) picoamperes per picofarad ( pA/pF) to (32.1±7.1) pA/pF (P<0.01). The expression level of Kv1.5 mRNA in passively sensitized HBSMCs was significantly lower than that in the control group (0.76±0.07 vs 1.04±0.13, P<0.05). The expression of Kv1.5 protein of passively sensitized HBSMCs was also significantly reduced compared to that from the control group (984±168 vs 2200±380, P<0.05).Conclusions The activity and expression of Kv were all decreased in HBSMCs passively sensitized by asthmatic serum compared with nonsensitized cells. These changes might be involved in the mechanisms of formation and development of asthma.
文摘Background：Stellate ganglion （SG） plays an important role in cardiovascular diseases.The electrical activity of SG neurons is involved in the regulation of the autonomic nervous system.The aim of this research was to evaluate the effects offluvastatin on the electrophysiological characteristics of SG neurons in a rabbit model of myocardial ischemia （MI）.Methods：The MI model was induced by abdominal subcutaneous injections of isoproterenol in rabbits.Using whole-cell patch clamp technique,we studied the characteristic changes of ion channels and action potentials （APs） in isolated SG neurons in control group （n =20）,MI group （n =20） and fluvastatin pretreated group （fluvastatin group,n =20）,respectively.The protein expression of sodium channel in SG was determined by immunohistochemical analysis.Results：MI and the intervention of fluvastatin did not have significantly influence on the characteristics of delayed rectifier potassium channel currents.The maximal peak current density of sodium channel currents in SG neurons along with the characteristics of activation curves,inactivation curves,and recovery curves after inactivation were changed in the MI group.The peak current densities of control group,MI group,and fluvastatin group （n =10 in each group） were-71.77 ± 23.22 pA/pF,-126.75 ± 18.90 pA/pF,and-86.42 ± 28.30 pA/pF,respectively （F=4.862,P =0.008）.Fluvastatin can decrease the current amplitude which has been increased by MI.Moreover,fluvastatin induced the inactivation curves and post-inactive recovery curves moving to the position of the control group.But the expression of sodium channel-associated protein （Nav 1.7） had no significantly statistical difference among the three groups.The percentages of Nav 1.7 protein in control group,MI group,and fluvastatin group （n =5 in each group） were 21.49 ± 7.33%,28.53 ± 8.26%,and 21.64 ± 2.78%,respectively （F =1.495,P =0.275）.Moreover,MI reduced the electrical activity of AP and increased amplitude of AP,fluvastatin pretreatment could recover amplitude and electrical activity of AP.The probability of neurons induced continuous APs were 44.44%,14.29%,and 28.57% in control group,MI group,and fluvastatin group,respectively.Conclusions：Fluvastatin pretreatment can recover electrophysiology characteristics of ion channel and AP in SG neurons in a rabbit model of MI.It could be considered as potential method for treating coronary heart diseases.
