Efficacy and safety comparison between pro-urokinase and reteplase in the treatment of patients with acute ST elevation myocardial infarction / 中华心血管病杂志

Objective: To compare the efficacy and safety of pro-urokinase and reteplase in the treatment of patients with acute ST elevation myocardial infarction (STEMI). Methods: STEMI patients, who received intravenous thrombolytic therapy in Henan STEMI registry between September 2016 and August 2018, were eligible for this study. A total of 5479 patients from 66 hospitals were screened and patients were divided into pro-urokinase group (n=638) and reteplase group (n=702) according to thrombolytic drugs. Data including patient demographics, risk factors, medical histories, patient information at admission, in-hospital treatment, time delays, and clinical events were collected. The clinical recanalization rate, in-hospital mortality, in-hospital death or treatment withdrawal, in-hospital main adverse cardiovascular and cerebrovascular events (MACCE, death or treatment withdrawal, congestive heart failure, reinfarction and ischemic stroke) and post-thrombolysis bleeding were compared between the two groups. Bleeding events were evaluated with Bleeding Academic Research Consortium (BARC) criteria. Results: The median age [61.8 (53.2, 69.0) vs. 62.6 (52.1, 69.8), P=0.833] or the proportion of women [23.0% (147/638) vs. 25.1% (176/702), P=0.385] were similar between the pro-urokinase and reteplase groups. Clinical recanalization rates were similar between the pro-urokinase and reteplase groups [82.1% (524/638) vs. 84.9% (596/702), P=0.172], and there was no difference in the median time from onset to thrombolysis [194.5 (135.0,290.0) min vs. 190 (126.0,292.0) min, P=0.431] and the median recanalization time [95 (67.5,120.0) min vs. 95 (71.0,119.0) min, P=0.561] between the two groups. There was no significant difference in in-hospital mortality [5.5% (35/638) vs. 5.1% (36/702), P =0.770], in-hospital all-cause mortality, treatment withdrawal [8.9% (57/638) vs.7.7% (54/702), P=0.410], and in-hospital MACCE [13.0% (83/638) vs. 10.4% (73/702), P=0.137] between pro-urokinase and reteplase groups. However, the incidence of post-thrombolysis bleeding was significantly higher in reteplase group than in pro-urokinase group [7.8% (55/702) vs. 3.8% (24/638), P=0.002]. Further analysis found that the incidence of oral bleeding and the BARC grades 1-2 bleeding were significantly higher in reteplase group than in pro-urokinase group, whereas the incidence of cerebral hemorrhage was similar between the two groups [0.6% (4/638) vs. 0.4% (3/702), P=0.715]. The comparison of efficacy and safety outcomes between the two groups after adjusting for baseline characteristics using general linear mixed models was consistent with those before the adjustment. There was no significant difference in in-hospital mortality, in-hospital death or treatment withdrawal, in-hospital MACCE after adjusting for baseline characteristics and post-thrombolysis bleeding between the two groups. Conclusions: Pro-urokinase and reteplase have similar clinical efficacy in the treatment of STEMI. In terms of safety, the incidence of cerebral hemorrhage is similar, while the incidence of BARC grades 1-2 bleeding and oral bleeding is higher in reteplase group than in pro-urokinase group, which has no impact on in-hospital outcomes.

Effect of Kv1.3 and KCa3.1 potassium ion channels on the proliferation and migration of monocytes/macrophages / 生理学报

This study was aimed to investigate the effects of blockade of Ca(2+) activated channel KCa3.1 and voltage-gated potassium channel Kv1.3 of the monocytes/macrophages on inflammatory monocyte chemotaxis. Chemotaxis assay was used to test the inflammatory Ly-6C(hi) monocyte chemotaxis caused by the monocytes/macrophages. The proliferation of monocytes/macrophages was detected by cell counting kit-8 (CCK8). Enzyme-linked immunosorbent assay (ELISA) was applied to detect the C-C motif ligand 7 (CCL7) in cultured media. The results showed that the recruitment of Ly-6C(hi) monocyte induced by monocytes/macrophages was suppressed by the potent Kv1.3 blocker Stichodactyla helianthus neurotoxin (ShK) or the specific KCa3.1 inhibitor TRAM-34. Meanwhile, the proliferation of monocytes/macrophages was significantly inhibited by ShK. The response of Ly-6C(hi) monocyte pretreated with ShK or TRAM-34 to CCL2 was declined. These results suggest that KCa3.1 and Kv1.3 may play an important role in monocytes/macrophages' proliferation and migration.

Expression of tissue factor in rabbit pulmonary artery in an acute pulmonary embolism model / 世界急诊医学杂志（英文）

BACKGROUND:Tissue factor (TF) is the initiation factor of the extrinsic coagulation pathway, and plays a critical role in the process of thrombosis. This study aimed to investigate the expression of TF and to explore their clinical effect on the pulmonary artery after acute pulmonary thromboembolism. METHODS:Thirty-four Japanese white rabbits (Level II animals) supplied by Tianjin Medical University were randomly assigned into:group A, specimens of the pulmonary artery taken 3 hours after pulmonary embolism (n=8); group B, specimens of the pulmonary artery taken 8 hours after pulmonary embolism (n=8); group C, specimens of the pulmonary artery taken 24 hours after pulmonary embolism (n=8); and control group, pseudo-operations performed without injection of autologous blood clots (n=10). The animal model of pulmonary thrombo-embolism was established by injection of autologous blood clots into the jugular vein through a 5F catheter, and was confirmed by digital subtraction angiography. The mRNA expression of TF in different parts of the pulmonary artery was accessed by RT-PCR. Theq test was used if there was a significant difference in a given continuous variable among the three groups assessed by ANOVA. The experiment equipment was supplied by the State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, the Chinese Academy of Medical Sciences and Peking Union Medical College. RESULTS:The TF expression in the specimen adjacent to emboli was stable at 3, 8 or 24 hours after embolism. The mRNA expression of TF at 3 and 8 hours after embolism was lower in the specimens taken from the distal end of the morbid pulmonary artery than those adjacent to emboli. While at 24 hours after embolism, there were similar mRNA levels in specimens either adjacent or distal to emboli. CONCLUSION:The high level of TF expression in pulmonary artery tissue adjacent to emboli could lead to locally increased coagulation activity, indicating the necessity of initiating anti-coagulation treatment as soon as possible after acute pulmonary embolism.

Efficacy and safety of tirofiban use after successful percutaneous coronary intervention for patients with moderate to high risk non-ST segment elevation acute coronary syndromes / 中华心血管病杂志

<p><b>OBJECTIVE</b>To evaluate the efficacy and safety of tirofiban use immediately after successful percutaneous coronary intervention (PCI) in patients with moderate to high risk non-ST segment elevation acute coronary syndromes (NSTE-ACS).</p><p><b>METHODS</b>NSTE-ACS patients undergoing successful PCI (n = 246) were randomized by the envelope method to tirofiban group (n = 122, 10 µg/kg bolus within 3 min followed by 0.10-0.15 µg×kg(-1)×min(-1) for 36 h i.v.) or control group (n = 124, saline i.v. for 36 h). The primary efficacy composite end point was death, myocardial infarction, target vascular revascularization or ischemic stroke at 30 days. The second end point was the occurrence of composite end point at 7 days or 6 months. Key safety end points were bleeding and thrombocytopenia 3 days after PCI.</p><p><b>RESULTS</b>Baseline characteristics were well-balanced between the two groups (P > 0.05). The primary end point occurred in 0.9% (1/117) patients in the tirofiban group and 3.3% (4/123) patients of those in the control group (P = 0.40). There was no significant difference in the composite end point at 7 days [0.8% (1/122) vs. 3.2% (4/124), P = 0.38] between the groups, however, there was a trend towards lower composite efficacy end points at 6 months in tirofiban group compared to control group [0.9% (1/117) vs. 5.9% (7/118), P = 0.07]. The probability of survival free of composite end point was significantly higher in the tirofiban group than that in the control group (99.2% vs. 94.2%, log-rank test, P = 0.03). There was no GUSTO severe or moderate bleeding or severe thrombocytopenia within 3 days post-PCI. There was no significant difference in mild bleeding [13.1% (16/122) vs. 7.3% (9/124), P = 0.13] or mild thrombocytopenia [0.8% (1/122) vs. 0.8% (1/124), P = 1.00] between the groups.</p><p><b>CONCLUSION</b>Tirofiban use after successful PCI can improve 6-month event-free survival without increasing the risk of bleeding for patients with moderate to high risk NSTE-ACS.</p>

Angiotensin(1-7) attenuates left ventricular dysfunction and myocardial apoptosis on rat model of adriamycin-induced dilated cardiomyopathy / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the effect of Angiotensin(1-7) [Ang(1-7)] on left ventricular dysfunction and myocardial apoptosis on rat model of adriamycin-induced dilated cardiomyopathy (ADR-DCM).</p><p><b>METHODS</b>Weight-matched adult male Wistar rats were randomly divided into 3 groups: (1) the ADR-DCM group (n = 25), in which 2.5 mg/kg of ADR was weekly intravenously injected for 10 weeks. (2) Ang(1-7) group (n = 25), in which ADR rats were simultaneously treated with angiotensin-(1-7) (24 µg×kg(-1)×h(-1), ip.) for 12 weeks. (3) normal control group (n = 10). Hemodynamics and echocardiography examination were performed at 12 weeks. The malondialdehyde (MDA) was measured by TBA methods. The plasma concentration of AngII was determined by immunoradiometric assay. The pathological change was analyzed by histological hematoxylin-eosin staining. Myocardial apoptosis was assessed by TUNEL method. The protein expression of pro-apoptotic protein caspase-3, Bax and anti-apoptotic protein Bcl-xl in cardiomyocytes were detected by Western blot.</p><p><b>RESULTS</b>Mortality was significantly lower in Ang(1-7) group than in ADR-DCM group (16% vs. 40%, P < 0.01). Compared to the control group, left ventricular end-diastolic diameter (LVEDD), left ventricular end systolic diameter (LVESD) and left ventricular end-diastolic pressure (LVEDP) were significantly increased in ADR-DCM group (all P < 0.01) while fractional shorting (FS), +dp/dtmax and -dp/dtmax were significantly reduced in ADR-DCM group (all P < 0.01). LVEDD, LVESD and LVEDP were significantly reduced while FS, +dp/dtmax and -dp/dtmax were significantly higher in Ang(1-7) group compared to the ADR-DCM group, but still higher than the control group (all P < 0.01). The concentrations of AngII and MDA were higher in the ADR-DCM group than in the control group (P < 0.01), which were significantly reduced by Ang(1-7) treatment (P < 0.01). The TUNEL-positive cells and apoptosis index, the expression of pro-apoptotic protein caspase-3 and Bax were significantly higher while the expression of anti-apoptotic protein Bcl-xl was significantly lower in the ADR-DCM group than in the control group (all P < 0.01) which could all be partially reversed by Ang(1-7) treatment (all P < 0.01).</p><p><b>CONCLUSION</b>Ang(1-7) could significantly attenuate left ventricular dysfunction and myocardial apoptosis in this model by downregulating pro-apoptotic protein caspase-3 and Bax and upregulating anti-apoptotic protein Bcl-xl expression.</p>

Predictive value of corrected QT interval, corrected Tp-e interval and Tp-e/QT ratio on malignant arrhythmia events in acute ST-segment elevation myocardial infarction patients undergoing thrombolysis / 中华心血管病杂志

<p><b>OBJECTIVE</b>The prognostic value of corrected QT interval (QTc), corrected Tp-e interval (Tp-ec) and Tp-e/QT ratio on occurrence of malignant arrhythmia events (MAE) in acute ST-segment elevation myocardial infarction (STEMI) patients underwent successful thrombolysis was explored and the potential association of these indices with MAE was analyzed.</p><p><b>METHODS</b>Fifty-seven STEMI patients underwent successful thrombolytic therapy within 6 hours after admission and conservative medical treatment were included. QTc, Tp-ec, Tp-e/QT ratio were obtained and calculated in infarct-related electrocardiograph leads and non-infarct-related leads before thrombolysis, (7±1) days and (30±3) days after thrombolysis respectively, and incidence of MAE up to 30 days after thrombolysis was analyzed. Sixty age and gender matched normal subjects served as control group.</p><p><b>RESULTS</b>(1) QTc, Tp-ec, Tp-e/QT in infarct-related and non-infarct-related leads in STEMI group before thrombolysis were significantly higher than those in control group (all P<0.05), and values from the infarct-related leads were significantly higher than those from non-infarct-related leads in STEMI group (all P<0.05). QTc, Tp-ec and Tp-e/QT all significantly and continuously reduced from 7 days and at 30 days post thrombolysis compared the before thrombolysis (P<0.05 vs. before thrombolysis). (2) Tp-ec≥100 ms and Tp-e/QT ratio≥0.25 before thrombolysis in infarct-related leads were linked with higher incidence of MAE within 30 days post thrombolysis in this patient cohort [28.1% (9/32) vs. 40% (1/25), 27.8% (10/36) vs.0, respectively, all P<0.05].</p><p><b>CONCLUSION</b>QTc, Tp-ec and Tp-e/QT values decreased post successful thrombolysis in STEMI patients and higher Tp-ec and Tp-e/QT values before thrombolysis in STEMI patients were related with higher MAE incidence up to 30 days post successful thrombolysis in this patient cohort.</p>

Comparative study on the efficacy of intracoronary infusion with various types of autologous bone marrow stem cells for patients with dilated cardiomyopathy / 中华心血管病杂志

<p><b>OBJECTIVE</b>To compare the effects of intracoronary infusion of mononuclear stem cells (MNCs) or mesenchymal stem cells (MSCs) in patients with dilated cardiomyopathy (DCM).</p><p><b>METHODS</b>DCM patients with left ventricular ejection fraction(LVEF) < 40% were randomized to intracoronary infusion of MNCs [(5.1 ± 2.0) × 10(8), n = 16] or MSCs [(4.9 ± 1.7) × 10(8), n = 17] or equal volume normal saline (n = 20) through the guiding catheter. Changes of left ventricular end-diastolic diameter (LVEDd), LVEF and myocardium perfusion defects were assessed before and at (30 ± 3) days and (90 ± 7) days after the procedure. Malignant cardiovascular events were also recorded.</p><p><b>RESULTS</b>(1) One month after the procedure, LVEF in transplantation groups significantly increased compared to before procedure (all P < 0.05), and significant increase of LVEF was observed only in MSCs transplantation group compared to control group (P < 0.05). However, absolute changes of LVEDd and perfusion defects of myocardium were similar among and within groups (P > 0.05). (2) Comparing with before procedure and control group, LVEF in transplantation groups increased significantly in three months after the procedure (P < 0.05), but there were no significant differences between transplantation groups (P > 0.05). LVEDd and myocardium perfusion defects in transplantation groups improved significantly compared with that of before procedure (P < 0.05), while significant decrease of myocardium perfusion defects was only observed in patients treated with MSCs compared with control group at three months after procedure (P < 0.05). (3) There were no significant differences in major cardiovascular events between transplantation group and control during follow-up (P > 0.05).</p><p><b>CONCLUSIONS</b>Intracoronary bone marrow stem cells transplantation is safe and effective for DCM patients while the efficacy of MSCs and MNCs transplantation is comparable.</p>

Effects of telmisartan on voltage-gated Kv1.3 and Kv1.5 potassium channels expressed in Xenopus oocytes / 中华心血管病杂志

<p><b>OBJECTIVE</b>To observe the effects of telmisartan on Kv1.3 and Kv1.5 potassium channels expressed in Xenopus oocytes.</p><p><b>METHODS</b>Kv1.3 and Kv1.5 potassium channel currents expressed in Xenopus oocytes were recorded and observed in the absence and presence of telmisartan using standard two-microelectrode voltage clamp techniques.</p><p><b>RESULTS</b>Telmisartan resulted in a concentration- and voltage-dependent inhibition effect on Kv1.3 channel current (IC(50) 2.05 micromol/L)and on Kv1.5 channel current (IC(50) 2.37 micromol/L).</p><p><b>CONCLUSIONS</b>Telmisartan blocks open-state Kv1.3 channel which could be one of the mechanisms related to its immunomodulatory and anti-atherosclerosis effect. Telmisartan also blocks open-state Kv1.5 channel which might partly account for its effect on reducing the incidence of atrial fibrillation.</p>

Blockade of the human ether-a-go-go-related gene potassium channel by ketanserin / 生理学报

In the present study, we investigated the inhibitory action of ketanserin on wild-type (WT) and Y652 mutant human ether-a-go-go-related gene (HERG) potassium channels expressed in Xenopus oocytes and the effects of changing the channel molecular determinants characteristics on the blockade with and without ketanserin intervention using standard two-microelectrode voltage-clamp techniques. Point mutations were introduced into HERG gene (Y652A and Y652R) and subcloned into the pSP64 plasmid expression vector. Complementary RNAs for injection into oocytes were prepared with SP6 Cap-Scribe after linearization of the expression construct with EcoR I. Clampfit 9.2 software was employed for data collection and analysis. Origin 6.0 software was used to fit the data, calculate time constants and plot histograms. The results showed that ketanserin blocked WT HERG currents in voltage- and concentration-dependent manner and showed minimal tonic blockade of HERG current evaluated by the envelope of tails test. The IC50 value was (0.38+/-0.04) micromol/L for WT HERG potassium channel. The peaks of the I-V relationship for HERG channel suggested a negative shift in the voltage-dependence of activation after using ketanserin, whose midpoint of activation values (V1/2) were (-16.59+/-1.01) mV (control) vs (-20.59+/-0.87) mV (ketanserin) at 0.1 micromol/L, (-22.39+/-0.94) mV at 1 micromol/L, (-23.51+/-0.91) mV at 10 micromol/L, respectively (P<0.05, n=6). Characteristics of blockade were consistent with an open-state channel blockade, because the extent and rate of onset of blockade was voltage-dependent, increasing at more potentials even in the condition of leftward shift of activation curve. Meanwhile, in the different depolarization duration, the fractional blockade of end-pulse step current and peak tail current at 100 ms duration was significantly lower than that at 400 ms and 700 ms, which indicated that following the channel activation fractional blockade was enhanced by the activated channels. Ketanserin could also modulate the inactivation of HERG channel, which shifted the voltage-dependence of WT HERG channel inactivation curve from (-51.71+/-2.15) mV to (-80.76+/-14.98) mV (P<0.05, n=4). The S6 mutation, Y652A and Y652R, significantly attenuated the blockade by ketanserin. The IC50 value were (27.13+/-9.40) micromol/L and (20.20+/-2.80) micromol/L, respectively, increased by approximately 72-fold for Y652A and 53-fold for Y652R compared to that of WT HERG channel blockade [(0.38+/-0.04) micromol/L]. However, between the inhibitory effects of Y652A and Y652R, there was no significant difference. In conclusion, ketanserin blocks WT HERG currents in voltage- and concentration-dependent manner and preferentially blocks open-state HERG channels. Tyr-652 is one of the critical residues in the ketanserin-binding sites.

High extracellular potassium ion concentration attenuates the blockade action of ketanserin on Kv1.3 channels expressed in xenopus oocytes / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Ketanserin (KT), a selective serotonin (5-HT) 2-receptor antagonist, reduces peripheral blood pressure by blocking the activation of peripheral 5-HT receptors. In this study electrophysiological method was used to investigate the effect of KT and potassium ion on Kv1.3 potassium channels and explore the role of blocker KT in the alteration of channel kinetics contributing to the potassium ion imbalances.</p><p><b>METHODS</b>Kv1.3 channels were expressed in xenopus oocytes, and currents were measured using the two-microelectrode voltage-clamp technique.</p><p><b>RESULTS</b>KCl made a left shift of activation and an inactivation curve of Kv1.3 current and accelerated the activation and inactivation time constant. High extracellular [K(+)] attenuated the blockade effect of KT on Kv1.3 channels. In the presence of KT and KCl the activation and inactivation time constants were not influenced significantly no matter what was administered first. KT did not significantly inhibit Kv1.3 current induced by tetraethylammonium (TEA).</p><p><b>CONCLUSIONS</b>KT is a weak blocker of Kv1.3 channels at different concentrations of extracellular potassium and binds to the intracellular side of the channel pore. The inhibitor KT of ion channels is not fully effective in clinical use because of high [K(+)](o) and other electrolyte disorders.</p>

The persistent expression of HERG channel in Xenopus oocyte and alteration of current / 中国应用生理学杂志

<p><b>AIM</b>To explore a method of the stable and persistent expression of HERG(human ether-a-go-go-related gene) channels in Xenopus oocytes, and investigate the alteration of rest membrane potential of oocytes and electrophysiological properties of expressed channel in different culture duration.</p><p><b>METHODS</b>HERG mRNA for injection was prepared with in intro transcription using vector plasmid pSP64 containing HERG cDNA fragment. Expressed HERG current was recorded using standard two-microelectrode voltage-clamp technique.</p><p><b>RESULTS</b>(1) Functional channels, with electrophysiological properties consistent with those of HERG channels were persistently expressed in oocytes membrane with this method. Furthermore, channel current could be recorded stably in 10-15 days. (2) The negative value of rest membrane potential increased gradually in the 3, 6, and 9 days of culture, and then decreased in the 12 days. The potential of peak value of inward rectification shifted gradually to the positive direction in 3, 6 and 9 days, and recovered in 12 days. Half-maximal activation potential (V1/2) of heterological expressed current shifted gradually to the negative direction in 3, 6 and 9 days of culture and then recovered in 12 days, the tendency of change was coincident with that of membrane rest potential.</p><p><b>CONCLUSION</b>The investigation provides a method of persistent expression of HERG channel in Xenopus oocytes and offers evidences for the difference of electrophysiological experimental data of studies of molecular site and drugs effect of HERG channel in different experimental conditions.</p>

Changes of blood lipids in colorectal cancer patients with coronary heart disease and value of lipid-lowering therapy with statins / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate the changes of blood lipid in patients with colorectal cancer complicated by coronary heart disease (CHD) and the effect of lipid-lowering therapy with statins in these patients.</p><p><b>METHODS</b>In 32 pathologically confirmed colorectal cancer patients with CHD, the concentrations of total cholesterol (TC), triglyceride (TG), high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C) and lipoprotein (a) (Lp(a)) were detected at the baseline, before and after the operation, and at 6 months of postoperative atorvastatin treatment. Thirty patients with TC over 5.70 mmol/L and established coronary artery disease served as the control group.</p><p><b>RESULTS</b>TC, TG and LDL-C in the 30 control patients were significantly decreased after 6 months of 20 mg atorvastatin treatment, and even further decreased till 12 months (P<0.01), but no significant changes occurred in HDL-C and Lp(a). The baseline level of TC, TG, LDL-C and HDL-C were significantly decreased (P<0.01), while Lp(a) increased (P<0.05) in the 32 cancer patients with CHD. Continuing atorvastatin treatment further decreased TC, TG and LDL-C (P<0.05) and increased HDL-C (P<0.05) without affecting Lp(a). The cancer patients had significantly lower TC and LDL-C levels than the control group (P<0.05), but had significantly increased Lp(a) (P<0.05). Six months of atorvastatin treatment further decreased LDL-C and HDL-C in the cancer patients (P<0.05), while TC and Lp(a) had no significant changes.</p><p><b>CONCLUSIONS</b>Increased Lp(a) in colorectal cancer patients can be associated with its anti-tumor effect. Alterations in the blood lipid profile raises a new issue concerning the safety of lipid-lowering therapy in colorectal cancer patients complicated by CHD.</p>

The effect of hypoxia-early reoxygenation on persistent sodium current in single ventricular myocytes of guinea pig / 中国应用生理学杂志

<p><b>AIM</b>To investigate the effect of hypoxia/early reoxygenation on persistent sodium current (I(Na.P)) in single ventricular myocytes of guinea pig and discuss its role and significance during this pathological condition.</p><p><b>METHODS</b>The whole cell patch clamp technology was used to record this current and study its change under the condition of hypoxia/reoxygenation model.</p><p><b>RESULTS</b>(1) With 0.5 Hz, 1 Hz and 2 Hz pulse frequency, the current density gap between the first and the eighth pulse of I(Na.P) was (0.021 +/- 0.014) pA/ pF, (0.097 +/- 0.014) pA/pF and (0.133 +/- 0.024) pA/pF (P < 0.01) respectively. (2) Depolarization with membrane holding potential of -150 - -80 mV respectively, I(Na.P) density attenuated gradually. (3) The amplitude of I(Na.P) was increased consistently with the prolongation of hypoxia time during hypoxia. (4) I(Na.P) was (0.500 +/- 0.125) pA/pF, (1.294 +/- 0.321) pA/pF and (0.988 +/- 0.189) pA/pF (P < 0.01, vs normoxia, respectively) during normoxia, hypoxia after 15 min and reoxygenation after 5 min, respectively.</p><p><b>CONCLUSION</b>These results indicate that I(Na.P) has great significance in arrhythmogenesis and calcium-overload, which causes the following postischemia and post hypoxia myocardial damage.</p>

Nitric oxide increases persistent sodium current of ventricular myocytes in guinea pig during normoxia and hypoxia / 生理学报

Whole cell patch-clamp technique was used to record the changes of persistent sodium current (I(Na.P)) and the effect of administered agents in ventricular myocytes of guinea pig to investigate the essence of I(Na.P) and mechanism of increased I(Na.P) of ventricular myocytes during hypoxia. The results showed: (1) Pro-NO L-arginine(L-Arg) and donor sodium nitroprusside (SNP) increased I(Na.P) in a concentration-dependent manner in normoxia. (2) I(Na.P) increased gradually with the prolongation of hypoxia time. After 15 min of hypoxia, administration of N(G)-nitro-L-arginine methyl ester (L-NAME), a NO synthase inhibitor, could not significantly recover the increased I(Na.P) [(1.344+/-0.320) vs (1.301+/-0.317) pA/pF, P>0.05, n=5]; (3) During hypoxia the perfusion solution with L-NAME decreased the increased I(Na.P), and the difference was significant compared with pure hypoxia [(0.914+/-0.263), n=5 vs (1.344+/-0.320) pA/pF, P<0.05, n=6], whereas the amplitude of I(Na.P) was still larger than that in normoxia [(0.914+/-0.263) vs (0.497+/-0.149) pA/pF, P<0.05, n=5]; (4) Reducing agent dithiothreitiol (DTT) not only recovered the increased I(Na.P) by L-Arg and administered SNP after hypoxia [(1.449+/-0.522) vs (0.414+/-0.067) pA/pF, P<0.01, n=6, and (1.786+/-0.636) vs (0.436+/-0.141) pA/pF, P<0.01, n=5, respectively], but also decreased the I(Na.P) in normoxia [(0.442+/-0.056) vs (0.396+/-0.057) pA/pF, P<0.01, n=6]. Our results suggest that hypoxia increases I(Na.P) of ventricular myocytes, which is induced by raised NO oxidating sodium channel protein in myocardial membrane during hypoxia. The activity of I(Na.P) in normoxia is related to the oxidation state of the channel protein.