B.-F. Yang’s research while affiliated with Harbin Medical University and other places

Growing evidence suggests that long-term abuse of ketamine does harm the heart and increases the risk of sudden death. The present study was performed to explore the cardiotoxicity of ketamine and the protective effects of metoprolol. Rats and rabbits were divided into control, ketamine, metoprolol alone and ketamine plus metoprolol groups. Ketamine (40 mg·kg(-1) ·day(-1), i.p.) and metoprolol (20 mg·kg(-1) ·day(-1), p.o.) were administered continuously for 12 weeks in rats and 8 weeks in rabbits. Cardiac function, electrophysiological disturbances, cardiac collagen, cardiomyocte apoptosis and the remodelling-related proteins were evaluated. Rabbits treated with ketamine showed decreased left ventricular ejection fraction, slowed ventricular conduction velocity and increased susceptibility to ventricular arrhythmia. Metoprolol prevented these pathophysiological alterations. In ketamine-treated rats, cardiac collagen volume fraction and apoptotic cell number were higher than those of control animals; these effects were prevented by co-administration of metoprolol. Consistently, the expressions of poly (ADP-ribose) polymerases-1, apoptosis-inducing factor and NF-κB-light-chain-enhancer of activated B cells were all increased after ketamine treatment and sharply reduced after metoprolol administration. Moreover, ketamine enhanced sympathetic sprouting, manifested as increased growth-associated protein 43 and tyrosine TH expression. These effects of ketamine were prevented by metoprolol. Chronic treatment with ketamine caused significant ventricular myocardial apoptosis, fibrosis and sympathetic sprouting, which altered the electrophysiological properties of the heart and increased its susceptibility to malignant arrhythmia that may lead to sudden cardiac death. Metoprolol prevented the cardiotoxicity of ketamine, indicating a promising new therapeutic strategy.

Arrhythmia is a common complication of cardiovascular diseases and a risk factor for human health. Especially, ventricular tachycardia and ventricular fibrillation may not only exacerbate original heart diseases, but also cause cardiac sudden death which has been an mportant death reason in China. However, anti-arrhythmic drugs nowadays cannot effectively treat these arrhythmias, with an efficiency of only 30%-60%, which indicates that our knowledge about arrhythmias is limited. Hence, to explore the potential mechanism, look for novel targets, and develop drugs with multiple-channel action are the focus of the research direction. Recent studies displayed that the atrial-specific potassium channels such as IKur and IKAch were involved in atrial fibrillation, which provided a prospective target for atrial fibrillation treatment. Calcium leak, gap junction protein and autoantibody against ICaL channel were shown to participate in arrhythmogenesis. These findings provided a theoretical basis for the development of more effective anti-arrhythmic drugs. Remarkably, as a kind of mportant RNA regulating gene expression, microRNA (miRNA) was shown to possess anti-arrhythmic activities which may prevent cardiac sudden death. miR-1, miR-133 and miR-590 regulated the arrhythmia in various types of animal models. Because of the multiple-gene regulation actions of miRNA, it has the potential to be developed as novel anti-arrhythmic target.

OBJECTIVE: To compare the influence of two kinds arsenic trioxide (As 2O3) treatment on activity of MMPs and cell invasion in NB4 cells. METHODS: NB4 cell line were treated with steady and changing concentrations of As2O3 in vitro respectively. The cell death was investigated by MTT assay. The activities of MMPs were detected by enzyme-linked immunosorbent assay, and their expressions were measured by western blotting and gelatinase zymography. The migration capabilities of NB4 at baseline and after being treated with the two kinds of different As 2O3 treatment were evaluated by transwell assay. RESULTS: Circled digit one With As2O3 continuous treatment in steady concentration: the MMPs activity and migration of NB4 cells were not significantly decreased by 0.1 μmol·L-1 As 2O3 for 72 h. The activity was remarkably inhibited by As2O3 in 0.5 μmol·L-1 for 72 h, in 1.0 μmol·L-1 for 48 h and in 2.0 μmol·L -1 and above 24 h compared with the parallel control. Circled digit two The inhibition effects of As2O3 on MMPs activity and migration of NB4 with As2O3 in 2.0 μmol·L -1 steady concentration treatment were remarkable compared with that in changing concentration treatment in vitro, even though the peak of As 2O3 concentration was 5.0 μmol·L-1. CONCLUSION: As2O3 with lower concentration could not inhibit MMPs activity and invasion of NB4 effectively. however, As 2O3 at higher apoptosis effective concentration decreased the MMPs activity and inhibited NB4 invasion remarkably in a concentration- and time-dependent manner. The inhibition efficiency of As2O3 on MMPs activity and NB4 cell invasion treated with general speed As 2O3, which has a fluctuated serum arsenic and a long pause of apoptosis non-effective lower arsenical level in serum between the two dosages of As2O3 administration, was less than that treated with the slow-steady speed As2O3 infusion, which can keep a relatively constant promoting apoptosis effective level of serum arsenic during the whole As2O3 infusion treatment.

Aim: To investigate the direct effects and mechanism of carvedilol on HERG channel stably expressing in human embryonic kidney-293 (HEK293) cells. Methods: Whole-cell patch-clamp technique was used to record HERG current and kinetic curves in single cells. Western blot methods were used to investigate the expression of HERG channel in different concentration of carvedilol. Result: Carvedilol decreased HERG current in a concentration-dependent manner with an IC50 539.6 nmol·L-1, Hillslope -0.64. The time constants of onset of inactivation and deactivation were accelerated. Other kinetcs (activation, inactivation, recovery from inactivation) had no significant changes. Based on western result, carvedilol had no effect on the generation and trafficking of HERG protein. Conclusion: Carvedilol inhibits the transfected HERG channels by influencing the open state which is the probable anti-arrhythmic mechanism. There is no relationship between carvedilol and HERG channel expression.

Aim: To investigate the effects of M3 receptor agonist choline on L-type calcium channels in guinea pig ventricular myocytes. Methods: Whole cell patch clamp technique was used to record L-type calcium current. Laser scanning confocal microscope ( LSCM ) was employed to measure the concentration of intracellular free calcium. Results: The application of 10 mmol · L-1 choline reduced the density of peak ICa-L from(9. 02 ± 0. 82) pA/pF to(5. 61 ± 0. 55) pA/pF (n = 4, P < 0. 01). ICa-L came back to (8. 12 ± 0. 65) pA/pF after the application of 5 nmol · L-1 4-DAMP. Choline remarkably shifted activation curve to the right, and delayed the voltage-dependent steady-state activation of calcium current. The half activation potential ( V1/2 ) was ( -18. 62 ± 1. 14 ) mV in the control and ( -21. 40 ± 1. 12) mV in the presence of choline 10 mmol · L-1 ( n = 6, P < 0. 05). Steady-state inactivation curve and the recovery time from inactivation were not affected markedly. LSCM recorded that KCl induced determined by used [ Ca 2+ ]i increasing could be depressed by choline ( 10 mmol · L-1 ) and the effect of choline could be blocked by 4-DAMP ( 5 nmol · L-1 ). Conclusion: Choline slows the activation procession of ICa-L and decreased [ Ca2+ ]i in ventricular myocytes will help its cardiac protection.

OBJECTIVE To investigate the effects of arsenic trioxide (As 2O3) on potassium current in guinea pig ventricular myocytes and to further explore the ionic targets of As2O2 -induced QT prolongation. METHODS Enzyme digestion was used to isolate single cardiomyocyte of guinea pig. Whole cell patch-clamp technique was utilized to record action potential duration (APD), delayed rectifier potassium current (IK ) and inward rectifier potassium current ( IKI). RESULTS Compared with control groups, APD50 was prolonged from (273 ±78) ms to (456 ±35) ms ( P <0. 01) and (513 ±41) ms ( P<0. 01) for 50 and 100 μmol · L-1 As2O 2, respectively. APD90 at the same doses of As 2O3 groups was also prolonged from (286 ±82) ms to (468 ±36) ms (P <0. 01) and (524 ±40) ms (P <0. 01). At the testing potential of +70 mV, As2O250 and 100 μnol-L-1 decreased IK from (6. 7 ±1.7) pA/ pF to (4. 9 ± 1. 6) pA/pF (P < 0. 05) and (4. 5 ± 1. 8 ) pA/pF (P < 0. 05), respectively. At the testing potential of - 120 mV, As 2O350 and 100 μnol-L reduced IKI from ( -20 ±5) pA/pF to ( - 13 ±3) pA/pF (P<0. 05) and ( -11 +2) pA/pF (P < 0. 05), respectively. CONCLUSION The ionic mechanism of As 2O3 -induced QT prolongation may be relative to disturbing the normal equilibrium of transmembrane currents (inhibiting IK and IK1) and causing prolongation of APD.

Aim: To explore the relationship between calcium and arrhythmia resulted from cerebral-cardiac syndrome (CCS) by studying the change and its source of the myocardium Intracellular frre calcium concentration Methods: The CCS model was produced by occluding right middle cerebral artery with nylon thread. The ECG were monitored. Cadiocyte were then isolated enzyme. The changes and pathway of the ventricular myocytes [ Ca2+ ]i were observed with Laser Scanning Confocal Microscope. Results: QT intervals in CCS group were remarkably longer than that in sham group and normal group(P < 0. 0 1). [Ca2+]i increasing induced by KCl in CCS group was significantly higher than that in sham group in Tyrode' s solution ( P < 0. 05) ; [ Ca2+ ]i increasing induced by KCl was obviously inhibited by 10 μmol · L-1 verapmil (P < 0. 01) after preincubation with verapamil (1 μmol · L -2 and 10 μmol · L -1) In CCS group in tyrode's solution. [ Ca2+ ]i increasing induced by caffeine in CCS group was significantly higher than that in sham group in calcium free tyrode's solution(P < 0. 01). Conclusion: Abnormal [ Ca2+ ]i increasing mediated by L-calcium channel and ryanodine receptor in sarcoplasmic reticulum may be one of the reasons of arrhythmia resulted from CCS.

Objective: To study the level of serum lipids and body-fat content of high-fat diet induced obesity rats (DIO), explore the relationship between intracellular calcium and ventricular arrhythmia. Methods: Sixty male Sprague-Dawley (SD) rats were divided into control group (15) and experiment group (45), high-fat diet was administrated for 12 weeks to established obesity model, 15 rats were selected into obesity group according to their body weight gain. The standard 2-lead electrocardiograph was used to detect the incidence and scores of arrhythmia induced by barium chloride (BaCl 2, 0.1 mg/kg) for 1 hour on every 8 rats from different groups respectively. Body-fat content, the level of serum total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and high density lipoprotein cholesterol (HDL-C) were measured. The epididymal (EP), retroperitoneal (RE) and mesenteric (ME) white adipose pads was measured to obtain the body fat content. Single ventricular myocytes of rats were isolated by enzymatic dissociation. The confocal laser scanning microscope was used to record basic intracellular calcium level ([Ca 2+] i). Results: The body-fat content in obesity group[(7.71 ± 0.74)%] was significantly higher than control group[(4.69 ± 0.37)%] (t = 3.650, P < 0.05). The level of serum TC, TG and LDL-C were significantly higher (t = 3.801, 2.778, 3.536, P < 0.05) in obesity group[(1.26 ± 0.04), (0.58 ± 0.10), (0.51 ± 0.04) mmol/L] than those in control group[(0.92 ± 0.08) (0.29 ± 0.03) (0.31 ± 0.04) mmol/L]. The level of serum HDL-C was decreased gradually from control group [(0.53 0.05)mmol/L] to obesity group [(0.52 ± 0.02) mmol/L], but there was no significant difference between them (t = 0.186, P > 0.05). The incidence of arrhythmia induced by BaCl 2 (0.1 mg/kg) in obesity group was significantly higher than control group (χ 2 = 5.333, P < 0.05), and the scores of arrhythmia was increased in obesity group (2.5 ± 0.6) too. The fluorescence intensity standing for [Ca 2+] i was increased significantly (t = 2.409, P < 0.05) from obesity group (247.96 ± 20.03) to control group (174.25 ± 23.13). Conclusion: As the free cytosolic calcium begin to accumulate, the arrhythmia morbidity is increased in obesity rats.

Aim: To observe the protective effects of choline and pilocarpine, the M3 receptor agonists, on the arrhythmias of Wistar rats induced by barium chloride. Methods: Barium chloride was used to induce the experimental arrhythmias of Wistar rats. Choline, pilocarpine, and 4-diphenylacetoxy-N-methylpiperidine-methiodide (4-DAMP), the selective antagonist of M3 receptor, were used to explore the effects of M3 receptor on the arrhythmias induced by barium chloride. The occurence and the severity of arrhythmias were observed. Results: Choline 10 mg · kg-1 and pilocarpine 0.2 mg · kg-1 inhibited the occurence of arrhythmias, shortened the duration of arrhythmias (P < 0.01) and decreased the score of Mest (severity of arrhythmias) (P < 0.01). However, the beneficial effects were reversed (P <0.05) by 4-DAMP 0.12 μg · kg-1, the selective antagonist of M3 receptor. Conclusion: Both choline and pilocarpine have protective effects on the arrhythmias of Wistar rats induced by barium chloride by activating the myocardial M3 receptor.