Background It has been proved that sevoflurane postconditioning （SpostC） could protect the heart against myocardial ischemia/reperfusion injury, however, there has been few research focused on the electrophysiologic...Background It has been proved that sevoflurane postconditioning （SpostC） could protect the heart against myocardial ischemia/reperfusion injury, however, there has been few research focused on the electrophysiological effects of SpostC. The objective of the study was to investigate the effects of SpostC on action potential duration （APD） and L-type calcium current （Ica, L） in isolated cardiomyocytes. Methods Langendorff perfused SD rat hearts were randomly assigned to one of the time control （TC）, ischemia/reperfusion （I/R, 25 minutes of ischemia followed by 30 minutes of reperfusion）, and SpostC （postconditioned with 3% sevoflurane） groups. At the end of reperfusion, epicardial myocytes were dissociated enzymatically for patch clamp studies. Results Sevoflurane directly prolonged APD and decreased peak Ica, L densities in epicardial myocytes of the TC group （P〈0.05）. I/R injury shortened APD and decreased peak Ica, L densities in epicardial myocytes of the I/R group （P〈0.05）. SpostC prolonged APD and increased peak Ica, L densities in epicardial myocytes exposed to I/R injury （P〈0.05）. SpostC decreased intracellular reactive oxygen species （ROS） levels, reduced the incidence of ventricular tachycardia and ventricular fibrillation, and decreased reperfusion arrhythmia scores compared with the I/R group （all P〈0.05）. Conclusions SpostC attenuates APD shortening and Ica, L suppression induced by I/R injury. The regulation of APD and lea, L by SpostC might be related with intracellular ROS modulation, which contributes to the alleviation of reperfusion ventricular arrhvthmia.展开更多
Background Endometrial carcinoma is one of the most common female tract genital malignant tumors. Nifedipine, an L-type calcium channel antagonist can inhibit cell proliferation of carcinomas. Recent studies indicated...Background Endometrial carcinoma is one of the most common female tract genital malignant tumors. Nifedipine, an L-type calcium channel antagonist can inhibit cell proliferation of carcinomas. Recent studies indicated that a rise in the free cytosolic calcium （[Ca2±]c） was a potent inducer of autophagy. Here, we investigated the relationship between nifedipine and autophagy in Hec-IA cells. Methods Cells were cultured with nifedipine （10 μmol/L） and harvested at different times for counting cell number. MTT assay was applied to evaluate the cell viability and transwell assay to reveal cell migration. Apoptotic cells were detected with annexin V/PI assay. Then cells were treated with 3-methyladenine （3-MA） （2.5 mmol/L） for 0, 5, 15, 30, 60, and 120 minutes and the expression of the L-type calcium channel alphalD （Cavl.3） protein was detected. At last, cells were cultured and assigned to four groups with different treatment： untreated （control group）, 10 μmol/L nifedipine （N group）, 2.5 mmol/L 3-MA （3-MA group）, and 10 μmol/L nifedipine plus 2.5 mmol/L 3-MA （N±3MA group）. Autophagy was detected with GFP-LC3 modulation by fluorescent microscopy, and expression of the autophagy-associated proteins （LC3, Beclinl and P70s6K） by Western blotting and monodansylcadaverine （MDC） labeled visualization. Results Proliferation of Hec-lA cells was obviously suppressed by nifedipine compared with that of the untreated cells for 24, 48, and 96 hours （P=0.000 for each day）. The suppression of migration ability of the nifedipine-treated cells （94.0±8.2） was significantly different from that of the untreated cells （160.00±9.50, P=0.021 ）. The level of early period cell apoptosis induced by nifedipine was （2.21_±0.19）%, which was （2.90±0.13）% in control group （P=-0.052）, whereas the late period apoptosis level reached （10.38_±0.96）% and （4.40_±0.60）% （P=0.020）, respectively. The 3-MA group induced a slight increase in the Cavl.3 levels within展开更多
With aim of providing constraints on the Late Paleozoic tectonic evolution of the southern Central Asian Orogenic Belt(CAOB),an integrated study was conducted on the geochronological and geochemical data for dioritic,...With aim of providing constraints on the Late Paleozoic tectonic evolution of the southern Central Asian Orogenic Belt(CAOB),an integrated study was conducted on the geochronological and geochemical data for dioritic,granitic and diabase dykes from the Aqishan-Yamansu belt in the eastern Tianshan,NW China.Zircon U-Pb dating indicates that the dioritic and granitic dykes were both emplaced in the Late Carboniferous(~311 Ma and^315 Ma).The dioritic dykes show adakitic characteristics and have high Na2 O and positiveεHf(t)values(+12 to+17),which suggest an origin from partial melts of a subducted oceanic slab.The granitic dykes have high SiO2 and K2 O contents and are characterized by en riched light rare earth elements(LREE)and slightly flat heavy rare earth elements(HREE),with negative Eu and Nb-Ta-Ti anomalies.These dykes are alkali-calcic and show geochemical features of highly fractionated Itype granites.Their positiveεHf(t)values(+16 to+17)suggest that they were derived from a juvenile accreted oceanic crustal sou rce.The coeval diabase dykes have low SiO2 and K2 O contents but high TiO2,MgO and Mg#(54-59).They are enriched in LREE and show characteristics of enriched mid-ocean ridge basalts(E-MORB).The relatively high Ba/Th,slightly low Th/Ta ratios,and negative Nb-Ta anomalies imply a mantle source metasomatised by slab-derived fluids.Thus,these basic dykes were generated likely by partial melting of the upwelling asthenosphere mantle with a slight influence of slab-derived fluids.Therefore,we suggest that the formation of these Late Carboniferous dykes were triggered by a post-collisional slab breakoff and the Aqishan-Yamansu belt was a continental arc formed by southdipping subduction of the Kangguer oceanic plate.展开更多
Diabetes mellitus affects the heart through various mechanisms such as microvascular defects,metabolic abnormalities,autonomic dysfunction and incompatible immune response.Furthermore,it can also cause functional and ...Diabetes mellitus affects the heart through various mechanisms such as microvascular defects,metabolic abnormalities,autonomic dysfunction and incompatible immune response.Furthermore,it can also cause functional and structural changes in the myocardium by a disease known as diabetic cardiomyopathy(DCM)in the absence of coronary artery disease.As DCM progresses it causes electrical remodeling of the heart,left ventricular dysfunction and heart failure.Electrophysiological changes in the diabetic heart contribute significantly to the incidence of arrhythmias and sudden cardiac death in diabetes mellitus patients.In recent studies,significant changes in repolarizing K+currents,Na+currents and L-type Ca^(2+)currents along with impaired Ca^(2+ )homeostasis and defective contractile function have been identified in the diabetic heart.In addition,insulin levels and other trophic factors change significantly to maintain the ionic channel expression in diabetic patients.There are many diagnostic tools and management options for DCM,but it is difficult to detect its development and to effectively prevent its progress.In this review,diabetes-associated alterations in voltage-sensitive cardiac ion channels are comprehensively assessed to understand their potential role in the pathophysiology and pathogenesis of DCM.展开更多
In the present study,we investigated the mechanisms underlying the mediation of iron transport by Ltype Ca^2+ channels(LTCCs)in primary cultured ventral mesencephalon(VM)neurons from rats.We found that cotreatment wit...In the present study,we investigated the mechanisms underlying the mediation of iron transport by Ltype Ca^2+ channels(LTCCs)in primary cultured ventral mesencephalon(VM)neurons from rats.We found that cotreatment with 100 lmol/L FeSO4 and MPP^+(1-methyl-4-phenylpyridinium)significantly increased the production of intracellular reactive oxygen species,decreased the mitochondrial transmembrane potential and increased the caspase-3 activation compared to MPP^+ treatment alone.Co-treatment with 500 lmol/L CaCl2 further aggravated the FeSO4-induced neurotoxicity in MPP^+-treated VM neurons.Co-treatment with 10 lmol/L isradipine,an LTCC blocker,alleviated the neurotoxicity induced by co-application of FeSO4 and FeSO4/CaCl2.Further studies indicated that MPP^+treatment accelerated the iron influx into VM neurons.In addition,FeSO4 treatment significantly increased the intracellular Ca^2+ concentration.These effects were blocked by isradipine.These results suggest that elevated extracellular Ca^2+ aggravates ironinduced neurotoxicity.LTCCs mediate iron transport in dopaminergic neurons and this,in turn,results in elevated intracellular Ca^2+ and further aggravates iron-induced neurotoxicity.展开更多
Objective： To study the effect of salvianolic acid A （SAA） on L-type calcium current （I-CaL） in isolated ventdcular myocytes of Sprague-Dawley rats. Methods： SPA powder was dissolved in normal Tyrode＇s solution...Objective： To study the effect of salvianolic acid A （SAA） on L-type calcium current （I-CaL） in isolated ventdcular myocytes of Sprague-Dawley rats. Methods： SPA powder was dissolved in normal Tyrode＇s solution to reach the concentrations of 1, 10, 100, and 1000 μmol/L. The traditional whole-cell patch-clamp recording technique was employed to evaluate the effects of SAA on I-CaL in single ventricular myocytes which were prepared by Langendorff perfusion apparatus from Sprague-Dawley rats. Results： SPA （1, 10, 100, and 1000 μmol/L） inhibited I-CaL peak value by 16.23%± 1.3% （n=6, P〈0.05）, 22.9% ± 3.6% （n=6, P〈0.05）, 53.4% ± 3.0% （n=8, P〈0.01）, and 62.26% ± 2.9% （n=8, P〈0.01）, respectively. SAA reversibly inhibited I-CaL in a dose-dependent manner and with a half-blocking concentration （IC50） of 38.3 μmol/L. SAA at 100 μmol/L elevated the I-V curve obviously, and shifted the half-active voltage （V0.5） from （-15.78± 0.86） mV to （-11.24 ± 0.77） mV （n=6, P〈0.05） and the slope （K） from 5.33 ±0.74 to 4.35±0.74 （n=6, P〉0.05）. However, it did not alter the shapes of I-V curve, steady-state inactivation curve, or recovery from inactivation curve. Conclusions： SAA inhibited I-CaL in a dose-dependent manner. It shifted the steady-state activation curve to a more positive voltage, which indicated that the drug affected the activated state of calcium channels, and suggested that the Ca2. antagonistic effect of SPA be beneficial in the treatment of myocardial ischemia reperfusion injury.展开更多
As a noninvasive technique,ultrasound stimulation is known to modulate neuronal activity both in vitro and in vivo.The latest explanation of this phenomenon is that the acoustic wave can activate the ion channels and ...As a noninvasive technique,ultrasound stimulation is known to modulate neuronal activity both in vitro and in vivo.The latest explanation of this phenomenon is that the acoustic wave can activate the ion channels and further impact the electrophysiological properties of targeted neurons.However,the underlying mechanism of low-intensity pulsed ultrasound(LIPUS)-induced neuro-modulation effects is still unclear.Here,we characterize the excitatory effects of LIPUS on spontaneous activity and the intracellular Ca^(2+)homeostasis in cultured hippocampal neurons.By whole-cell patch clamp recording,we found that 15 min of 1-MHz LIPUS boosts the frequency of both spontaneous action potentials and spontaneous excitatory synaptic currents(sEPSCs)and also increases the amplitude of sEPSCs in hippocampal neurons.This phenomenon lasts for>10 min after LIPUS exposure.Together with Ca^(2+)imaging,we clarified that LIPUS increases the[Ca^(2+)]cyto level by facilitating L-type Ca^(2+)channels(LTCCs).In addition,due to the[Ca^(2+)]cyto elevation by LIPUS exposure,the Ca^(2+)-dependent CaMKII-CREB pathway can be activated within 30 min to further regulate the gene transcription and protein expression.Our work suggests that LIPUS regulates neuronal activity in a Ca^(2+)-dependent manner via LTCCs.This may also explain the multi-activation effects of LIPUS beyond neurons.LIPUS stimulation potentiates spontaneous neuronal activity by increasing Ca^(2+)influx.展开更多
We have studied transmembrane La3+ movement in rat ventricular myocytes for the first time by using the whole-cell patch-clamp recording mode. La3+ (0.01-5.0 mmol/L) could not bring out inward currents through the L-t...We have studied transmembrane La3+ movement in rat ventricular myocytes for the first time by using the whole-cell patch-clamp recording mode. La3+ (0.01-5.0 mmol/L) could not bring out inward currents through the L-type calcium channel in rat ventricular myocytes, while it could enter the cells by the same way carried by 1μmo1/L ionomycin. When the outward Na+ concentration gradient is formed, La3+ can enter the cells via Na-Ca exchange, and the exchange currents increase with the increase of external La3+ concentrations. But compared with Na-Ca exchange currents in the same concentration, the former is only 14%-38% of the latter. The patch-clamp experiment indicates that La3+ normally can not enter ventricular myocytes through L-type calcium channel, but it can enter the cells via Na-Ca exchange.展开更多
基金This work was supported by the grant Irom the National Natural Science Foundation of China （No. 81070098） and Foundation for Postgraduates＇ Innovative Research of Peking Union Medical College （No. 2010-1002-004）.
文摘Background It has been proved that sevoflurane postconditioning （SpostC） could protect the heart against myocardial ischemia/reperfusion injury, however, there has been few research focused on the electrophysiological effects of SpostC. The objective of the study was to investigate the effects of SpostC on action potential duration （APD） and L-type calcium current （Ica, L） in isolated cardiomyocytes. Methods Langendorff perfused SD rat hearts were randomly assigned to one of the time control （TC）, ischemia/reperfusion （I/R, 25 minutes of ischemia followed by 30 minutes of reperfusion）, and SpostC （postconditioned with 3% sevoflurane） groups. At the end of reperfusion, epicardial myocytes were dissociated enzymatically for patch clamp studies. Results Sevoflurane directly prolonged APD and decreased peak Ica, L densities in epicardial myocytes of the TC group （P〈0.05）. I/R injury shortened APD and decreased peak Ica, L densities in epicardial myocytes of the I/R group （P〈0.05）. SpostC prolonged APD and increased peak Ica, L densities in epicardial myocytes exposed to I/R injury （P〈0.05）. SpostC decreased intracellular reactive oxygen species （ROS） levels, reduced the incidence of ventricular tachycardia and ventricular fibrillation, and decreased reperfusion arrhythmia scores compared with the I/R group （all P〈0.05）. Conclusions SpostC attenuates APD shortening and Ica, L suppression induced by I/R injury. The regulation of APD and lea, L by SpostC might be related with intracellular ROS modulation, which contributes to the alleviation of reperfusion ventricular arrhvthmia.
基金This study was supported by a grant from the National Natural Science Foundation of China （No. 30973182）.
文摘Background Endometrial carcinoma is one of the most common female tract genital malignant tumors. Nifedipine, an L-type calcium channel antagonist can inhibit cell proliferation of carcinomas. Recent studies indicated that a rise in the free cytosolic calcium （[Ca2±]c） was a potent inducer of autophagy. Here, we investigated the relationship between nifedipine and autophagy in Hec-IA cells. Methods Cells were cultured with nifedipine （10 μmol/L） and harvested at different times for counting cell number. MTT assay was applied to evaluate the cell viability and transwell assay to reveal cell migration. Apoptotic cells were detected with annexin V/PI assay. Then cells were treated with 3-methyladenine （3-MA） （2.5 mmol/L） for 0, 5, 15, 30, 60, and 120 minutes and the expression of the L-type calcium channel alphalD （Cavl.3） protein was detected. At last, cells were cultured and assigned to four groups with different treatment： untreated （control group）, 10 μmol/L nifedipine （N group）, 2.5 mmol/L 3-MA （3-MA group）, and 10 μmol/L nifedipine plus 2.5 mmol/L 3-MA （N±3MA group）. Autophagy was detected with GFP-LC3 modulation by fluorescent microscopy, and expression of the autophagy-associated proteins （LC3, Beclinl and P70s6K） by Western blotting and monodansylcadaverine （MDC） labeled visualization. Results Proliferation of Hec-lA cells was obviously suppressed by nifedipine compared with that of the untreated cells for 24, 48, and 96 hours （P=0.000 for each day）. The suppression of migration ability of the nifedipine-treated cells （94.0±8.2） was significantly different from that of the untreated cells （160.00±9.50, P=0.021 ）. The level of early period cell apoptosis induced by nifedipine was （2.21_±0.19）%, which was （2.90±0.13）% in control group （P=-0.052）, whereas the late period apoptosis level reached （10.38_±0.96）% and （4.40_±0.60）% （P=0.020）, respectively. The 3-MA group induced a slight increase in the Cavl.3 levels within
基金supported by National Natural Science Foundation of China (Grant Nos.41421002and 41603028)MOST Special Fund from the State Key Laboratory of Continental Dynamics
文摘With aim of providing constraints on the Late Paleozoic tectonic evolution of the southern Central Asian Orogenic Belt(CAOB),an integrated study was conducted on the geochronological and geochemical data for dioritic,granitic and diabase dykes from the Aqishan-Yamansu belt in the eastern Tianshan,NW China.Zircon U-Pb dating indicates that the dioritic and granitic dykes were both emplaced in the Late Carboniferous(~311 Ma and^315 Ma).The dioritic dykes show adakitic characteristics and have high Na2 O and positiveεHf(t)values(+12 to+17),which suggest an origin from partial melts of a subducted oceanic slab.The granitic dykes have high SiO2 and K2 O contents and are characterized by en riched light rare earth elements(LREE)and slightly flat heavy rare earth elements(HREE),with negative Eu and Nb-Ta-Ti anomalies.These dykes are alkali-calcic and show geochemical features of highly fractionated Itype granites.Their positiveεHf(t)values(+16 to+17)suggest that they were derived from a juvenile accreted oceanic crustal sou rce.The coeval diabase dykes have low SiO2 and K2 O contents but high TiO2,MgO and Mg#(54-59).They are enriched in LREE and show characteristics of enriched mid-ocean ridge basalts(E-MORB).The relatively high Ba/Th,slightly low Th/Ta ratios,and negative Nb-Ta anomalies imply a mantle source metasomatised by slab-derived fluids.Thus,these basic dykes were generated likely by partial melting of the upwelling asthenosphere mantle with a slight influence of slab-derived fluids.Therefore,we suggest that the formation of these Late Carboniferous dykes were triggered by a post-collisional slab breakoff and the Aqishan-Yamansu belt was a continental arc formed by southdipping subduction of the Kangguer oceanic plate.
文摘Diabetes mellitus affects the heart through various mechanisms such as microvascular defects,metabolic abnormalities,autonomic dysfunction and incompatible immune response.Furthermore,it can also cause functional and structural changes in the myocardium by a disease known as diabetic cardiomyopathy(DCM)in the absence of coronary artery disease.As DCM progresses it causes electrical remodeling of the heart,left ventricular dysfunction and heart failure.Electrophysiological changes in the diabetic heart contribute significantly to the incidence of arrhythmias and sudden cardiac death in diabetes mellitus patients.In recent studies,significant changes in repolarizing K+currents,Na+currents and L-type Ca^(2+)currents along with impaired Ca^(2+ )homeostasis and defective contractile function have been identified in the diabetic heart.In addition,insulin levels and other trophic factors change significantly to maintain the ionic channel expression in diabetic patients.There are many diagnostic tools and management options for DCM,but it is difficult to detect its development and to effectively prevent its progress.In this review,diabetes-associated alterations in voltage-sensitive cardiac ion channels are comprehensively assessed to understand their potential role in the pathophysiology and pathogenesis of DCM.
基金supported by grants from the National Natural Science Foundation of China(81671249)the Natural Science Foundation of Shandong Province,China(ZR2016CM04).
文摘In the present study,we investigated the mechanisms underlying the mediation of iron transport by Ltype Ca^2+ channels(LTCCs)in primary cultured ventral mesencephalon(VM)neurons from rats.We found that cotreatment with 100 lmol/L FeSO4 and MPP^+(1-methyl-4-phenylpyridinium)significantly increased the production of intracellular reactive oxygen species,decreased the mitochondrial transmembrane potential and increased the caspase-3 activation compared to MPP^+ treatment alone.Co-treatment with 500 lmol/L CaCl2 further aggravated the FeSO4-induced neurotoxicity in MPP^+-treated VM neurons.Co-treatment with 10 lmol/L isradipine,an LTCC blocker,alleviated the neurotoxicity induced by co-application of FeSO4 and FeSO4/CaCl2.Further studies indicated that MPP^+treatment accelerated the iron influx into VM neurons.In addition,FeSO4 treatment significantly increased the intracellular Ca^2+ concentration.These effects were blocked by isradipine.These results suggest that elevated extracellular Ca^2+ aggravates ironinduced neurotoxicity.LTCCs mediate iron transport in dopaminergic neurons and this,in turn,results in elevated intracellular Ca^2+ and further aggravates iron-induced neurotoxicity.
基金Supported by the Key Project of National Science Foundation of China(No.30830118)the National Key New Drug Project (No.2009ZX09301-005 and No.2009ZX09303-003)
文摘Objective： To study the effect of salvianolic acid A （SAA） on L-type calcium current （I-CaL） in isolated ventdcular myocytes of Sprague-Dawley rats. Methods： SPA powder was dissolved in normal Tyrode＇s solution to reach the concentrations of 1, 10, 100, and 1000 μmol/L. The traditional whole-cell patch-clamp recording technique was employed to evaluate the effects of SAA on I-CaL in single ventricular myocytes which were prepared by Langendorff perfusion apparatus from Sprague-Dawley rats. Results： SPA （1, 10, 100, and 1000 μmol/L） inhibited I-CaL peak value by 16.23%± 1.3% （n=6, P〈0.05）, 22.9% ± 3.6% （n=6, P〈0.05）, 53.4% ± 3.0% （n=8, P〈0.01）, and 62.26% ± 2.9% （n=8, P〈0.01）, respectively. SAA reversibly inhibited I-CaL in a dose-dependent manner and with a half-blocking concentration （IC50） of 38.3 μmol/L. SAA at 100 μmol/L elevated the I-V curve obviously, and shifted the half-active voltage （V0.5） from （-15.78± 0.86） mV to （-11.24 ± 0.77） mV （n=6, P〈0.05） and the slope （K） from 5.33 ±0.74 to 4.35±0.74 （n=6, P〉0.05）. However, it did not alter the shapes of I-V curve, steady-state inactivation curve, or recovery from inactivation curve. Conclusions： SAA inhibited I-CaL in a dose-dependent manner. It shifted the steady-state activation curve to a more positive voltage, which indicated that the drug affected the activated state of calcium channels, and suggested that the Ca2. antagonistic effect of SPA be beneficial in the treatment of myocardial ischemia reperfusion injury.
基金supported by the National Key Research&Development Program of China(2022YFC3602700 and 2022YFC3602702)the Science and Technology Innovation 2030—Brain Science and Brain-Inspired Intelligence Project(2021ZD0201301)+5 种基金the National Natural Science Foundation of China(32170688,31971159,and 12034015)the Innovation Program of Shanghai Municipal Education Commission(2019-01-07-00-07-E00041)the Shanghai Municipal Science and Technology Major Project(2018SHZDZX01)the ZJ Labthe Shanghai Center for Brain Science and Brain-Inspired Technology,the Program of Shanghai Academic Research Leaders(21XD1403600)the Fundamental Research Funds for the Central Universities(22120230562).
文摘As a noninvasive technique,ultrasound stimulation is known to modulate neuronal activity both in vitro and in vivo.The latest explanation of this phenomenon is that the acoustic wave can activate the ion channels and further impact the electrophysiological properties of targeted neurons.However,the underlying mechanism of low-intensity pulsed ultrasound(LIPUS)-induced neuro-modulation effects is still unclear.Here,we characterize the excitatory effects of LIPUS on spontaneous activity and the intracellular Ca^(2+)homeostasis in cultured hippocampal neurons.By whole-cell patch clamp recording,we found that 15 min of 1-MHz LIPUS boosts the frequency of both spontaneous action potentials and spontaneous excitatory synaptic currents(sEPSCs)and also increases the amplitude of sEPSCs in hippocampal neurons.This phenomenon lasts for>10 min after LIPUS exposure.Together with Ca^(2+)imaging,we clarified that LIPUS increases the[Ca^(2+)]cyto level by facilitating L-type Ca^(2+)channels(LTCCs).In addition,due to the[Ca^(2+)]cyto elevation by LIPUS exposure,the Ca^(2+)-dependent CaMKII-CREB pathway can be activated within 30 min to further regulate the gene transcription and protein expression.Our work suggests that LIPUS regulates neuronal activity in a Ca^(2+)-dependent manner via LTCCs.This may also explain the multi-activation effects of LIPUS beyond neurons.LIPUS stimulation potentiates spontaneous neuronal activity by increasing Ca^(2+)influx.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 29890280).
文摘We have studied transmembrane La3+ movement in rat ventricular myocytes for the first time by using the whole-cell patch-clamp recording mode. La3+ (0.01-5.0 mmol/L) could not bring out inward currents through the L-type calcium channel in rat ventricular myocytes, while it could enter the cells by the same way carried by 1μmo1/L ionomycin. When the outward Na+ concentration gradient is formed, La3+ can enter the cells via Na-Ca exchange, and the exchange currents increase with the increase of external La3+ concentrations. But compared with Na-Ca exchange currents in the same concentration, the former is only 14%-38% of the latter. The patch-clamp experiment indicates that La3+ normally can not enter ventricular myocytes through L-type calcium channel, but it can enter the cells via Na-Ca exchange.
