Evaluation of cardiac safety of hydroxyrutaecarpine, hERG channel inhibitor / 药学学报

Drug-induced long QT syndrome (LQTS) has become an important clinical research topic, and the occurrence of acquired long QT syndrome (acLQTS) is mainly caused by drug inhibition of the human ether-α-go-go related gene (hERG) channel. The hERG gene encodes the α subunit of the fast-activating delayed rectifying potassium ion channel (Ikr), which plays an important role in the process of action potential phase 3 repolarization and is also the target of most antiarrhythmic drugs. The purpose of this study was to investigate the effect of hydroxyrutaecarpine (HRU) on the hERG channel and to evaluate its cardiotoxicity. The whole cell patch clamp technique was used to detect the effects of HRU on the current and kinetics of the hERG channel, and to confirm the binding site on the hERG channel. PCR was used to determine the effect of HRU on hERG mRNA expression. Western blotting was used to detect the effects of HRU on the expression of hERG protein and transcription factor Sp1. Immunofluorescence was used to confirm the effects of HRU on localization and expression of hERG protein and transcription factor Sp1. Studies have shown that transient HRU can inhibit hERG current and shorten the inactivation time constant. Its binding sites to the hERG channel are F656 and Y652. After incubation for 24 h, HRU can reduce the expression of hERG protein, inhibit the hERG current, reduce the level of hERG mRNA, and reduce the expression of transcription factor Sp1 in the nucleus and hERG protein in the cytoplasm. Immunofluorescence experiments also showed the same results suggesting that the inhibition of Sp1 expression by HRU is the cause of the decreased expression of hERG mRNA. In conclusion, the acute inhibition of HRU accelerates the channel inactivation process and reduces the inactivation time constant by binding to the F656 and Y652 sites in the hERG channel, thus reducing the hERG current. In addition, HRU also inhibits the expression of hERG protein, mainly by inhibiting the expression of transcription factor Sp1, the transcription function of hERG channel protein is down-regulated, so that the hERG protein is reduced.

Advances in research on the mechanism of long-QT syndrome caused by traditional Chinese medicine affecting hERG potassium channel / 药学学报

Drug-induced cardiotoxicity is recently a major concern. Cardiotoxicity is the leading cause of drug withdrawal from the market. Long-QT syndrome is one of the most important manifestations of cardiotoxicity. hERG potassium channel is an important target of drug-induced arrhythmia and antiarrhythmia drugs. Traditional Chinese medicine is a traditional medicine in China with a long history and a wide range of clinical use. However, the multi-organ toxicity caused by traditional Chinese medicine is still a problem to be solved. Some traditional Chinese medicines already in clinical use have been withdrawn from the market because of their potential cardiotoxicity or severe arrhythmias. The cardiac toxicity of more than 50 kinds of traditional Chinese medicines causing arrhythmia was reported, while more than 20 of them are induced by affecting on the hERG potassium channels. Therefore, finding out the mechanism of drug-induced long-QT syndrome and the regulatory target of drug intervention is the key research goal in today's medical field. In this paper, we summarized the mechanisms of long-QT syndrome induced by traditional Chinese medicine with Ikr/hERG potassium channel as the main target. It provides a theoretical basis for the rational use of related traditional Chinese medicine in clinical practice, the avoidance of cardiac toxicity and the development of regulatory targets for drug intervention.

Cardiac safety evaluation of berberine combining with berberine-derived medicine / 药学学报

Drug-induced cardiotoxicity is a serious concern in recent years, and acquired long QT syndrome (LQTS) is an important manifestation of cardiotoxicity. hERG gene encodes the α subunit of the rapidly activated delayed rectifier potassium channel (Ikr), which plays an important role in action potential phase 3 repolarization. Drug inhibition of Ikr/hERG channel leads to prolonged QT interval, accompanied by Tdp malignant arrhythmia, which can cause sudden death. We studied the effect of berberines on the hERG K+ channels after combination with rosuvastatin and glibenclamide, and evaluated the cardiac safety of these drugs in combination. Whole cell patch clamp technique was used to detect the effect of the combinations of these drugs on hERG current on HEK293 cells stably expressing hERG gene. The results showed that the inhibitory effects of berberine or dihydroberberberine combined with rosuvastatin on hERG current were higher than single drug (P<0.05), but the combination had no effect on the kinetics of hERG channel. Berberine or dihydroberberberine combined with glibenclamide had higher inhibitory effects on hERG current than the application of single drug (P<0.05) while the time constant of hERG channel inactivation was shortened after the combination (P<0.05). In addition, the combination of berberine and glibenclamide inhibited hERG channel activation (P<0.05). In conclusion, our results demonstrated that the combination of berberine with rosuvastatin or glibenclamide significantly inhibited hERG current and the inhibition effects were higher than the application alone. Therefore, when the two drugs that have inhibitory effects on the hERG channel are combined, the risk of inducing prolonged QT interval is significantly increased, and therefore reducing cardiac safety.

Expression of Pref-1 and Related Chemokines during theDevelopment of Rat Mesenteric Lymph Nodes / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>The aim of this study was to investigate the ability of Pref-1+ adipocyte progenitor cells to mobilize into mesenteric lymph nodes (MLNs) and the dynamic expression of related chemokines during the development of rat MLNs.</p><p><b>METHODS</b>Immunohistochemical analyses were used to detect the expression of Pref-1 and related chemokines. Transmission electron microscopy (TEM) was used to observe the changes in ultrastructure of MLNs.</p><p><b>RESULTS</b>Cells containing lipid droplets were found in all rat MLNs at embryonic day (E) 18.5, 2 and 6 weeks (w) after birth, and they were similar to fibroblastic reticular cells (FRCs) or follicular dendritic cells (FDCs) under TEM. Pref-1+ adipocyte progenitor cells were found in all MLNs. The expression level of Pref-1 was significantly increased at 2 w after birth and decreased at 6 w after birth. The tendency of Cxcl12 expression was consistent with that of Pref-1 and was positively correlated with the expression of Pref-1 (P < 0.01; r = 0.897). At E18.5, Cxcl13, and Ccr7 were significantly expressed in the MLN anlage, but the expression level of Ccl21 was low. The expression level of Cxcl13, Ccr7, and Ccl21 in MLN were significantly increased at 2 w after birth (P < 0.05), while the expression of Ccr7 and Ccl21 were significantly decreased at 6 w after birth (P < 0.05).</p><p><b>CONCLUSION</b>Adipocyte progenitor cells are involved in the rat MLNs development through differentiation into FRC and FDC. The expression of the relevant chemokines during the development of MLNs is dynamic and may be related to the maintenance of lymph nodes self-balance state.</p>

Effects of 3-aminobenzamide on expressions of poly (ADP ribose) polymerase and apoptosis inducing factor in cardiomyocytes of rats with acute myocardial infarction / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Poly (ADP-ribose) polymerase (PARP) plays an important role in cell survival and death. However, the mechanisms involved are not fully understood. Therefore, we investigated the effect of inhibition of PARP on acute myocardial infarction (AMI) at different time points in rats.</p><p><b>METHODS</b>AMI was induced in rats by ligating the left anterior descending coronary artery. One group received 3-aminobenzamide (3-AB, a kind of PARP inhibitor) (30 mg/kg) by intraperitoneal injection. The changes of ultramicrostructure of cardiocytes in infarction region were noted, PARP cleavage was measured by Western blotting, and expressions of protein of PARP and apoptosis inducing factor (AIF) were measured by immunohistochemical staining after treatment with 3-AB for 2 hours, 4 hours, 6 hours, 1 week, 4 weeks and 8 weeks.</p><p><b>RESULTS</b>Few damages to the ultramicrostructure of cardiocytes were observed after treatment with 3-AB. PARP cleavage was detected as early as 4 hours and markedly increased by 6 hours following AMI without 3-AB, but was not found until 6 hours following AMI treated with 3-AB. There were significant differences between 3-AB and AMI groups at the same time points. The expression of PARP was observed gradually increased, but that of AIF was suppressed for 6 hours after treatment of 3-AB, compared with AMI groups in positive cells at the same time points. There was significantly less cleavage of PARP and more PARP expression in 3-AB treated group compared with AMI and control groups at all matched time points.</p><p><b>CONCLUSIONS</b>Our results suggest that 3-AB inhibits degradation of PARP, increases the expression of PARP protein, and suppresses the expression of AIF protein. Inhibition of PARP activity may protect cardiocytes in rats with AMI and reduce apoptosis.</p>

Probucol attenuates atrial autonomic remodeling in a canine model of atrial fibrillation produced by prolonged atrial pacing / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>We hypothesize that increased atrial oxidative stress and inflammation may play an important role in atrial nerve sprouting and heterogeneous sympathetic hyperinnervation during atrial fibrillation (AF). To test the hypothesis, we examined whether the antioxidant and anti-inflammatory treatment with probucol attenuates atrial autonomic remodeling in a canine model of AF produced by prolonged rapid right atrial pacing.</p><p><b>METHODS</b>Twenty-one dogs were divided into a sham-operated group, a control group and a probucol group. Dogs in the control group and probucol group underwent right atrial pacing at 400 beats per minute for 6 weeks, and those in the probucol group received probucol 1 week before rapid atrial pacing until pacing stopped. After 6-week rapid atrial pacing, general properties including left atrial structure and function, atrial hemodynamics and the inducibility and duration of AF were measured in all the groups. Atrial oxidative stress markers and serum C-reactive protein (CRP) concentration were estimated. The degree of nerve sprouting and sympathetic innervation at the right atrial anterior wall (RAAW) and the left atrial anterior wall (LAAW) were quantified by immunohistochemistry, atrial norepinephrine contents were also detected. Atrial beta-nerve growth factor (beta-NGF) mRNA and protein expression at the RAAW and LAAW were assessed by real-time quantitative RT-PCR and Western blotting respectively.</p><p><b>RESULTS</b>Atrial tachypacing induced significant nerve sprouting and heterogeneous sympathetic hyperinnervation, and the magnitude of nerve sprouting and hyperinnervation was higher in the RAAW than in the LAAW. Atrial beta-NGF mRNA and protein levels were significantly increased at the RAAW and LAAW, and the upregulation of beta-NGF expression was greater at the RAAW than at the LAAW in the control group. The beta-NGF protein level was positively correlated with the density of sympathetic nerves in all groups. Probucol decreased the increase of CRP concentration and attenuated atrial oxidative stress caused by atrial tachypacing. In addition, probucol could effectively inhibit atrial beta-NGF upregulation, significantly attenuate atrial nerve sprouting and heterogeneous sympathetic hyperinnervation, and dramatically reduce the inducibility and duration of AF.</p><p><b>CONCLUSIONS</b>The atrial over-expression of beta-NGF possibly caused by increased oxidative stress and inflammation may be the main mechanism underlying atrial autonomic remodeling during AF. Probucol attenuates atrial autonomic remodeling possibly by its antioxidant and anti-inflammatory actions.</p>

Effect of sophocarpine on HERG K+ channels / 药学学报

Human ether-a-go-go-related gene (HERG) encodes the rapid component of the cardiac delayed rectifier K+ current, which has an important effect on both proarrhythmia and antiarrhythmia. To investigate the effect of sophocarpine (SC) on HERG channel stably expressing in human embryonic kidney-293 (HEK293) cells, whole-cell patch-clamp technique was used to record HERG current and kinetic curves. As the result, it was found that SC inhibited HERG current in a concentration-dependent manner (10, 30, 100, and 300 micromol x L(-1)). At 0 mV, 10, 30, 100, and 300 micromol x L(-1) SC respectively inhibited IHERG by Istep ( 10.7 +/- 2.8)% , (11.3 +/- 5.5)% , (47.0 +/- 2.3)% and (53.7 +/- 2.5)% , and Itail (1.1 +/- 3.0)%, (17.1 +/- 3.3)%, (32.7 +/- 1.9)% (P < 0.05, n = 12) and (56.0 +/- 2.4)% (P < 0.05, n = 13). The time constants of inactivation, recovery from inactivation and onset of inactivation were accelerated. SC did not change other channel kinetics (activation and deactivation). It is concluded that SC inhibited the transfected HERG channels by influencing the inactivation state, which is the probable anti-arrhythmic mechanism.

Reversal effect and mechanism of arsenic trioxide on multidrug resistance of gastric carcinoma cells SGC7901 / 药学学报

The purpose of this study is to investigate the reversal effect and its mechanism of arsenic trioxide (As2O3) on multidrug resistance of gastric carcinoma cells. The concentration of vincristine (VCR) increased gradually to induce the drug resistance of gastric carcinoma cell SGC7901. MTT assay was used to determine the lethal effect of anticarcinogens on tumor cells and Western blotting assay was applied to determine the expression of P-glucoprotein (P-gp) and glutathione S-transferase (GST-s) in tumor cells. As a result, the resistance of SGC7901/VCR cells to VCR, fluorouracil and epirubicin was 16.56, 2.69 and 13.05 times, respectively, more than that of SGC7901 cells. After 24 h precondition with As2O3, RI of vincristine, fluorouracil and epirubicin decreased significantly (P < 0.05). Expression of P-gp and GST-s in resting SGC7901/VCR cells was significantly higher than that in carcinogen-sensitive SGC7901 cells. As2O3 decreased the expression of P-gp and GST-s in SGC7901/VCR cells significantly, while it showed no significant effect on carcinogen-sensitive SGC7901 cells. The result suggested that As2O3 could partly reverse drug resistance of SGC7901/VCR cells by probably the mechanism of decreasing the expression of P-gp and GST-s.

Effects of matrine, oxymatrine and resveratrol on HERG channel expression / 药学学报

Because HERG potassium channel has important effects on both proarrhythmia and antiarrhythmia, we use immunofluorescence and Western blotting methods to detect the expression of HERG channel of HERG-HEK cells in different concentrations of matrine, oxymatrine and resveratrol. The findings showed that both matrine (1 micromol x L(-1) ) and oxymatrine ( 1micromol x L (-1) ) increased HERG channel expression ( n = 5, P < 0. 05 ) , while matrine (100 micromol x L(-1) ) decreased HERG channel expression ( n = 5, P < 0. 05), resveratrol didn't affect HERG channel expression. In conclusion, different concentrations of matrine and oxymatrine affect HERG channel expression, while there is no relationship between resveratrol and HERG channel expression. It provides a theoretical support for the safety and mechanism of anti-arrhythmic drugs.

Effects of resveratrol on isolated thoracic aorta rings of rats / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the relaxative characteristics of resveratrol on thoracic aortic artery in the rat and its mechanism.</p><p><b>METHOD</b>We perfused the isolated rings and observed the response of NA-induced artery contraction to resveratrol under the Ca2+-contained and Ca2+-free bath solutions. In the same way were the effect of reveratrol on the vascular smooth muscle observed by adding two different concentration of KCl (30 and 80 mmol x L(-1)), and the effect on the contraction of the vascular smooth muscle depending on the intracellular calcium and extracellular calcium were also observed by adding NA. We also observed the effect of resveratrol on the contraction of rings induced by NA in the presence of L-NNA and Glibenclamide.</p><p><b>RESULT</b>Resveratrol relaxed rat aorta rings precontracted by NA in a dose-dependent manner. The relaxant effect of resveratrol on the rat rings of endothelium-denuded group was reduced compared with that of endothelium-intact group; the relaxant effect of resveratrol on rat rings was higher under the condition of Ca2+-free bath solution than that under the condition of Ca2+-contained bath solution. Resveratrol had a repressive effect on the aorta's contraction induced by intracellular calcium, but had no effect induced by extracellular calcium. Resveratrol relaxed the contractions induced by KCl 30 mmol x L(-1) as well as KCl 80 mmol x L(-1), but the contraction curve of KCl 80 mmol x L(-1) was shifted upward significantly. In the L-NNA group, the relaxant effect was attenuated by (26.0 +/- 4.6) %; but there was no change in the group of Glibenclamide ( P > 0.05).</p><p><b>CONCLUSION</b>The results indicate that resveratrol relaxes vascular smooth muscle in an endothelium dependent manner. The mechanisms for this phenomenon seem to be related with promoting synthesis and release of NO, opening Ca2+ activated K+ channel (KCa channel) as well as the inhibition of Ca2+ influx and release of Ca2+ from intracellular stores.</p>

Clinical and experimental study of cardiac effects of conventional dosage arsenic trioxide in APL patients / 中华血液学杂志

<p><b>OBJECTIVE</b>To investigate cardiac effects of arsenic trioxide (As(2)O(3)) at conventional dosage in acute promyelocytic leukemia (APL) patients.</p><p><b>METHODS</b>The basical heart rate, electrocardiograph, plasma As(2)O(3) concentration of APL patients were dynamically monitored. The action potential duration and current of I(Ca-L) in guinea pig cardiac ventricular myocytes were assayed by patch clamp technique, and the elevated cytosolic [Ca(2+)]i of guinea pig ventricular myocytes induced by As(2)O(3) by laser confocal microscopy.</p><p><b>RESULTS</b>Approximately 52.5% - 35% of 40 APL patients manifested poor cardiac effects of different degree when As(2)O(3) intravenous infused at conventional doses in the initial 1 or 2 weeks with fast heart rate or prolonged QT interval. As(2)O(3) at concentration of 1, 2, 5 micro mol/L prolonged action potential duration from (563.0 +/- 55.8) ms to (737.7 +/- 131.7), (842.4 +/- 115.6) and (1103.2 +/- 96.3) ms respectively (P < 0.05, P < 0.01, P < 0.01), and increased I(Ca-L) of guinea pig cardiac ventricular myocytes as well as the respectively cytosolic [Ca(2+)]i. Calcium channel blocking agent can cut-out the effect.</p><p><b>CONCLUSION</b>As(2)O(3) intravenous infusion at conventional doses can cause tachycardia and prolong QT interval. The probable mechanism might be that As(2)O(3) affects the ion channels and cytosolic calcium.</p>

Stereoselectivity in absorption of trans tramadol in rat intestine / 药学学报

<p><b>AIM</b>To investigate the stereoselectivity in absorption of trans tramadol (trans T) in rat intestine.</p><p><b>METHODS</b>The duodenum, jejunum and ileum were separately perfusated in situ with trans T dissolved in Krebs-Ringer buffer. Trans T enantiomers in the perfusate were analyzed with a high performance capillary electrophoresis (HPCE) method.</p><p><b>RESULTS</b>The absorbed fractions of trans T enantiomers were similar among the different segments of the rat intestine. The absorbed fraction of (+)-trans T was lower than that of (-)-trans T when the concentration of trans T was not higher than 40 mumol.L-1. As the concentration of trans T increased, the absorbed fractions of trans T enantiomers were reduced and the difference in absorbed fractions between trans T enantiomers became not significant.</p><p><b>CONCLUSION</b>Trans T enantiomers can be absorbed in different parts of the rat intestine. The intestinal absorption of trans T was stereoselective, (-)-trans T being preferentially absorbed.</p>