TBC1 domain family member 25 protects against myocardial apoptosis and the proinflammatory response triggered by ischemia-reperfusion injury through suppression of the TAK1-JNK/p38 MAPK signaling cascade.

TBC1 domain family member 25 (TBC1D25) is a crucial mediator of signal transduction involved in the development of several diseases. Particularly, a cardioprotective role of TBC1D25 has been raised due to its antagonistic action on cardiac hypertrophy. However, whether TBC1D25 protects the myocardium from ischemia-reperfusion injury has not been reported. This work aimed to determine the role of TBC1D25 in myocardial ischemia-reperfusion (MIR) injury and to explore the potential mechanisms involved. Marked decreases in TBC1D25 levels occurred in cardiomyocytes suffering hypoxia/reoxygenation (H/R) injury in vitro and myocardium tissues of rats with MIR injury in vivo. Cardiomyocytes overexpressing TBC1D25 were protected from apoptosis and inflammation triggered by H/R, whereas TBC1D25-deficient cardiomyocytes were more sensitive to H/R injury. Intramyocardial injection of recombinant adenovirus expressing TBC1D25 into rats reduced infarct size and cardiac injury triggered by MIR injury accompanied by decreased myocardial apoptosis and inflammation. A subsequent mechanistic investigation revealed that the signaling cascade of transforming growth factor-ß-activated kinase 1 (TAK1)-c-Jun N-terminal kinase (JNK)/p38 mitogen-activated protein kinase (MAPK) activated under H/R or MIR conditions was markedly restrained by TBC1D25 overexpression. Moreover, TAK1 blockade remarkably reversed the TBC1D25 deficiency-induced aggravating effect on H/R injury. The work concludes that TBC1D25 protects against MIR injury through action on the TAK1-JNK/p38 MAPK signaling cascade. This work suggests TBC1D25 as a potential therapeutic target for MIR injury.

Bakuchiol Alleviates Hyperglycemia-Induced Diabetic Cardiomyopathy by Reducing Myocardial Oxidative Stress via Activating the SIRT1/Nrf2 Signaling Pathway.

Bakuchiol (BAK), a monoterpene phenol reported to have exerted a variety of pharmacological effects, has been related to multiple diseases, including myocardial ischemia reperfusion injury, pressure overload-induced cardiac hypertrophy, diabetes, liver fibrosis, and cancer. However, the effects of BAK on hyperglycemia-caused diabetic cardiomyopathy and its underlying mechanisms remain unclear. In this study, streptozotocin-induced mouse model and high-glucose-treated cell model were conducted to investigate the protective roles of BAK on diabetic cardiomyopathy, in either the presence or absence of SIRT1-specific inhibitor EX527, SIRT1 siRNA, or Nrf2 siRNA. Our data demonstrated for the first time that BAK could significantly abate diabetic cardiomyopathy by alleviating the cardiac dysfunction, ameliorating the myocardial fibrosis, mitigating the cardiac hypertrophy, and reducing the cardiomyocyte apoptosis. Furthermore, BAK achieved its antifibrotic and antihypertrophic actions by inhibiting the TGF-ß1/Smad3 pathway, as well as decreasing the expressions of fibrosis- and hypertrophy-related markers. Intriguingly, these above effects of BAK were largely attributed to the remarkable activation of SIRT1/Nrf2 signaling, which eventually strengthened cardiac antioxidative capacity by elevating the antioxidant production and reducing the reactive oxygen species generation. However, all the beneficial results were markedly abolished with the administration of EX527, SIRT1 siRNA, or Nrf2 siRNA. In summary, these novel findings indicate that BAK exhibits its therapeutic properties against hyperglycemia-caused diabetic cardiomyopathy by attenuating myocardial oxidative damage via activating the SIRT1/Nrf2 signaling.

Taurine protects against cardiac dysfunction induced by pressure overload through SIRT1-p53 activation.

BACKGROUND: Heart failure (HF) is an epidemic disease with increased incidence annually. It has been reported that taurine can improve cardiac function. This study investigated the cardioprotective effects of taurine in pressure-loaded HF mice and elucidated the possible mechanism. METHODS: HF models were established by transverse aortic constriction (TAC). Animals were treated with either taurine for 9 weeks and/or the SIRT1 inhibitor EX527 (5 mg/kg/day, every 2days) after TAC operation. Cardiac function and geometry were revealed by echocardiography. Myocardial hypertrophy and fibrosis were assessed using Fluorescent wheat germ agglutinin (WGA) staining and Masson's trichrome staining. Western blot and RT-PCR were performed to elucidate the expression of target proteins and genes respectively. Apoptosis in cardiomyocytes was detected by TUNEL staining. Myocardial oxidative stress was assessed by detecting the concentration of myocardial super oxidative dismutase (SOD) and malonyldialdehyde (MDA) and reactive oxygen species (ROS). Taurine concentrations and NAD+/NADH ratio were determined by taurine and NAD+/NADH assay kit. RESULTS: Taurine notably relieved cardiac dysfunction after TAC. The mechanisms were attributed to reduced myocyte hypertrophy and fibrosis, and alleviated apoptosis and oxidative stress. Meanwhile, taurine increased NAD+/NADH ratio，promoted the expression of SIRT1 and suppressed p53 acetylation. However, EX-527(inhibitor of SIRT1) decreased NAD+/NADH ratio and increased acetyl-p53 levels, and abolished the cardioprotective effects of taurine on mice subjected to TAC and increased apoptosis and oxidative stress. CONCLUSION: The mechanism responsible for cardiac-protective effects of taurine in HF induced by pressure overload is associated with the activation of the SIRT1-p53 pathway.

Blocking PERK resuces vascular smooth muscle cells from homocysteine-induced ER stress and apoptosis.

Hyperhomocysteinemia induces stress response in endoplasmic reticulum (ERS). Here, we tested whether blockage of homocysteine (Hcy) induced ERS and subsequent apoptosis in vascular smooth muscle cells can be inhibited by  blockage of PERK/eIF2α/ATF4/CHOP signaling. Short-term exposure of vascular smooth muscle cells to Hcy led to the phosphorylation of PERK (pPERK), which in turn, phosphorylated eIF2 alpha (peIF2a) and inhibited the unfolded protein response. Long-term Hcy exposure, however, increased the expression of ATF-4 and CHOP and led to apoptosis. Treatment of cells with salubrinal, a specific inhibitor for eIF2a decreased the expression of ATF-4 and CHOP, and prevented apoptosis. Together, the results show that PERK pathway is involved in Hcy-induced vascular smooth muscle cell apoptosis and that blocking the PERK pathway protects against this injury.

Association of serum adropin with the presence of atrial fibrillation and atrial remodeling.

OBJECTIVE: Adropin, a newly identified regulatory protein encoded by Enho gene, suppressed tumor necrosis factor α-induced THP1 monocyte adhesion to human umbilical vein endothelial cells. In addition, inflammation is demonstrated to be involved in the mechanism of atrial fibrillation (AF). Atrial remodeling is correlated with the persistence and progression of AF. Adropin is hypothesized to correlated with AF and atrial remodeling. This study aims to determine the correlation of serum adropin and the presence of AF and remodeling. METHODS: This study consisted of 344 AF patients and 210 healthy controls. AF patients were then divided into three subgroups of paroxysmal AF, persistent AF, and permanent AF. Serum adropin concentrations were examined using enzyme-linked immunosorbent assay method. Left atrial diameter (LAD) was measured to evaluate atrial remodeling. RESULTS: Decreased serum adropin concentrations were found in AF patients compared with healthy controls. Logistic regression analysis confirmed that serum adropin was inversely associated with the presence of AF (OR 0.218, 95% CI 0.15-0.316; P < 0.001). Permanent AF patients had significantly reduced serum adropin concentrations compared with persistent and paroxysmal AF patients. There were decreased serum adropin concentrations in persistent AF group than those in paroxysmal AF group. Simple linear regression analyses showed that serum adropin in AF patients were negatively correlated with BMI, SBP, and LAD. Multiple stepwise regression analysis showed that LAD remained to be inversely associated with serum adropin (ß = 0.2, P = 0.010). CONCLUSION: Serum adropin concentrations are inversely correlated with the presence of AF and atrial remodeling.

Clinical Application of Superior Vena Cava Spectra in Evaluation of Pulmonary Hypertension: A Comparative Echocardiography and Catheterization Study.

This study was designed to assess whether superior vena cava (SVC) Doppler flow velocities are associated with invasive measures of pulmonary arterial pressure. Eighty patients with unrepaired congenital heart disease who underwent cardiac catheterization were included (31 men, 49 women; mean age: 37.3 ± 14.7 y). Compared with the non-pulmonary hypertension group, the moderate and severe pulmonary hypertension groups had decreased SVC ventricular reserve flow velocity and a significantly increased ratio of atrial reverse flow to systolic flow (AR/S). AR/S correlated significantly with invasive pulmonary arterial systolic pressure (r = 0.426, p < 0.0001). A cutoff of 0.45 had a sensitivity and specificity of 74% and 80%, respectively, for prediction of pulmonary hypertension. Good correlation also existed between SVC AR/S and pulmonary arterial systolic pressure in cases without tricuspid regurgitation (r = 0.706, p = 0.034). These results indicate that SVC AR/S may be an alternative method for assessing pulmonary hypertension.

Carotid Arterial Stiffness in Patients with Congenital Heart Disease-Related Pulmonary Hypertension Assessed with Radio Frequency Data Technique.

BACKGROUND: It has been well known that pulmonary hypertension (PH) caused by congenital heart disease (CHD) leads to reduced flexibility of the small pulmonary arteries, due to hemodynamic changes in the pulmonary circulation and alterations of the vasoactive profile. However, whether CHD-related PH affects the elasticity of the systemic arteries, such as the common carotid artery (CCA), has not been fully investigated. The purpose of this study was to explore the CCA stiffness in patients with CHD-related PH using the radio frequency data technique. METHODS: Forty patients with CHD were included. They were divided into PH and non-PH (NPH) groups by the right heart catheter-determined or regurgitation velocity-determined mean pulmonary arterial pressure (mPAP). MyLabTwice (Esaote, Genoa, Italy) ultrasound machine equipped with automatic quality intima-media thickness (QIMT) and quality arterial stiffness (QAS) capabilities was used to measure the left common carotid arterial (CCA) intima-media thickness and arterial stiffness parameters. RESULTS: The results have shown that the left CCA internal diameter, pulse wave velocity, arterial wall tension, and local diastolic pressure were increased in the CHD-related PH group compared with the CHD-related NPH group (all P < 0.05). The left CCA internal diameter negatively and significantly correlated with the mean PAP. CONCLUSIONS: Common carotid artery diameter and stiffness increase in patients with CHD-related pulmonary hypertension. QIMT and QAS ultrasound techniques may provide a comprehensive assessment of the CCA remodeling.

Validation of the iHealth BP5 wireless upper arm blood pressure monitor for self-measurement according to the European Society of Hypertension International Protocol revision 2010.

OBJECTIVE: The aim of this study was to validate the iHealth BP5 wireless upper arm blood pressure (BP) monitor according to the European Society of Hypertension International Protocol (ESH-IP) revision 2010. MATERIALS AND METHODS: The ESH-IP revision 2010 for validation of BP measuring devices in adults was followed precisely. A total of 99 pairs of test device and reference BP measurements (three pairs for each of the 33 participants) were obtained in the study. RESULTS: The device produced 71, 89, and 97 measurements within 5, 10, and 15 mmHg for systolic blood pressure (SBP) and 73, 90, and 99 mmHg for diastolic blood pressure (DBP), respectively. The mean ± SD device-observer difference was -1.21 ± 5.87 mmHg for SBP and -1.04 ± 5.28 mmHg for DBP. The number of participants with two or three device-observer differences within 5 mmHg was 25 for SBP and 28 for DBP. In addition, three participants had no device-observer difference within 5 mmHg for SBP and none of the participants had the same for DBP. CONCLUSION: According to the validation results on the basis of the ESH-IP revision 2010, the iHealth BP5 wireless upper arm BP monitor can be recommended for self/home measurement in an adult population.

Validation of the iHealth BP3 upper-arm blood pressure monitor, for clinic use and self-measurement, according to the European Society of Hypertension International Protocol revision 2010.

OBJECTIVE: This study aimed to evaluate the performance of the iHealth BP3 upper-arm blood pressure monitor, which is designed for clinic use and self-measurement of blood pressure using Apple touch devices as an interface. METHODS: The European Society of Hypertension International Protocol (ESH-IP) revision 2010 for the validation of blood pressure measuring devices in adults was followed precisely. Ninty-nine couples of test device and reference blood pressure measurements were obtained during the study (three pairs for each of the 33 participants). RESULTS: The 33 participants, age 47.1±12.3 years (age range 27-69 years) and arm circumference 30.0±4.4 cm, had a mean systolic blood pressure (SBP) of 143.9±27.4 mmHg and a mean diastolic blood pressure (DBP) of 90.1±18.3 mmHg. The device passed all of the requirements fulfilling the standards of the protocol, and the mean±SD device-observer difference was 2.8±4.2 mmHg for SBP and -0.4±3.5 mmHg for DBP. CONCLUSION: According to the results of the validation study on the basis of the ESH-IP revision 2010, the iHealth BP3 can be recommended for clinic use and self-measurement in an adult population.

Involvement of reactive oxygen species and JNK in increased expression of MCP-1 and infiltration of inflammatory cells in pressure-overloaded rat hearts.

Increasing evidence has shown that inflammation is involved in pressure overload-induced cardiac remodeling. Monocyte chemoattractant protein-1 (MCP-1) plays a pivotal role in the inflammatory process. However, the mechanisms underlying the upregulation of MCP-1 expression remain poorly understood. In the present study, we examined the hypothesis that an increased production of reactive oxygen species (ROS) mediates the upregulation of MCP-1. In a pressure-overloaded rat heart model with abdominal aortic coarctation (AC), superoxide dismutase-inhibitable cytochrome C reduction assay showed that ROS generation in the myocardium increased significantly at 1 week by 61% (n=8, P<0.01), peaked at 2 weeks and maintained these high levels for 4 weeks. The elevation of ROS was paralleled by the increased expression of MCP-1 and left ventricular remodeling (cardiac hypertrophy, perivascular and interstitial fibrosis). The oral administration of the antioxidant, N-acetylcysteine (NAC, 0.2 g/kg/day), for 2 or 4 weeks, significantly attenuated ROS production by 69 and 68%, respectively (n=8, P<0.01), as well as left ventricular remodeling. NAC treatment for 2 weeks also significantly reduced the MCP-1 mRNA and protein levels by 52 and 60%, respectively (n=4-8, both P<0.01), but had no effect on blood pressure. In the rats with AC at 2 weeks, when MCP-1 expression and inflammation changes were overt, immunoblotting with phospho-specific antibodies revealed that extracellular regulated kinase (ERK) and c-jun NH2-terminal kinase (JNK), but not p38 mitogen-activated protein kinase, were activated. NAC administration attenuated JNK activation, but had no effect on ERK. Our results suggest that increased ROS production may play an important role in the increased expression of MCP-1 in pressure overload-induced cardiac remodeling. JNK is likely involved in the signaling pathway.

A web-based appointment system to reduce waiting for outpatients: a retrospective study.

BACKGROUND: Long waiting times for registration to see a doctor is problematic in China, especially in tertiary hospitals. To address this issue, a web-based appointment system was developed for the Xijing hospital. The aim of this study was to investigate the efficacy of the web-based appointment system in the registration service for outpatients. METHODS: Data from the web-based appointment system in Xijing hospital from January to December 2010 were collected using a stratified random sampling method, from which participants were randomly selected for a telephone interview asking for detailed information on using the system. Patients who registered through registration windows were randomly selected as a comparison group, and completed a questionnaire on-site. RESULTS: A total of 5641 patients using the online booking service were available for data analysis. Of them, 500 were randomly selected, and 369 (73.8%) completed a telephone interview. Of the 500 patients using the usual queuing method who were randomly selected for inclusion in the study, responses were obtained from 463, a response rate of 92.6%. Between the two registration methods, there were significant differences in age, degree of satisfaction, and total waiting time (P<0.001). However, gender, urban residence, and valid waiting time showed no significant differences (P>0.05). Being ignorant of online registration, not trusting the internet, and a lack of ability to use a computer were three main reasons given for not using the web-based appointment system. The overall proportion of non-attendance was 14.4% for those using the web-based appointment system, and the non-attendance rate was significantly different among different hospital departments, day of the week, and time of the day (P<0.001). CONCLUSION: Compared to the usual queuing method, the web-based appointment system could significantly increase patient's satisfaction with registration and reduce total waiting time effectively. However, further improvements are needed for broad use of the system.

Serum omentin-1 levels are inversely associated with the presence and severity of coronary artery disease in patients with metabolic syndrome.

CONTEXT: Omentin-1, an adipokine secreted from visceral adipose tissue, has been reported to be associated with coronary artery disease (CAD) and metabolic disorders. OBJECTIVE: To clarify the relationship between serum omentin-1 levels and the presence and severity of CAD in patients with metabolic syndrome (MetS). METHODS: We measured serum omentin-1 levels in 175 consecutive patients with MetS and in 46 controls. RESULTS: Serum omentin-1 levels are inversely associated with the presence and angiographic severity of CAD in MetS patients. CONCLUSIONS: Serum omentin-1 might be a potential biomarker to predict the development and progression of CAD in MetS patients.

Validation of the Medipro MediCare 100f upper arm blood pressure monitor, for self-measurement, according to the European Society of Hypertension International Protocol revision 2010.

OBJECTIVE: The validation of sphygmomanometer is important in accurate blood pressure measurement. This study presents the validation results by the Medipro MediCare 100f upper arm blood pressure monitor according to the European Society of Hypertension International Protocol (ESH-IP) revision 2010. METHODS: The ESH-IP revision 2010 for the validation of blood pressure measuring devices in adults was followed precisely. A total of 99 couples of test device and reference blood pressure measurements were obtained during the study (three pairs for each of the 33 participants). RESULTS: The device produced 73, 93, and 98 measurements within 5, 10, and 15 mmHg for systolic blood pressure (SBP) and 79, 93, and 96 for diastolic blood pressure (DBP), respectively. The mean standard deviation device-observer difference was 1.4 ± 5.2 mmHg for SBP and 0.02±5.8 mmHg for DBP. The number of participants with two or three of the device-observer differences within 5 mmHg was 24 for SBP and 30 for DBP, whereas there was no participant with none of the device-observer differences within 5 mmHg. CONCLUSION: According to the results of the validation study based on the ESH-IP revision 2010, the Medipro MediCare 100f can be recommended for self-measurement in an adult population.

Increased Th17 cells in coronary artery disease are associated with neutrophilic inflammation.

OBJECTIVE: Atherosclerosis is a progressive disease characterized by a series of inflammatory responses in the large and medium arteries. Th17 cells, a distinct T cell lineage which has recently been identified, have a proinflammatory role and are implicated in many inflammatory conditions in humans and mice. The present study was designed to assess whether Th17 cells are associated with human coronary atherosclerosis. DESIGN: Flow cytometry was used to examine Th17 cell frequencies in patients with coronary atherosclerosis and in healthy individuals. ELISA and real-time RT-PCR were performed to investigate circulating interleukin (IL)-17 (the signature cytokine of Th17 cells) and IL-8 (the cytokine induced by IL-17) protein and mRNA levels. RESULTS: Significantly increased Th17 cell frequencies are observed in patients with coronary artery disease compared to healthy controls. The protein and mRNA levels of IL-17 and IL-8 are also significantly elevated in patients with atherosclerosis compared to healthy volunteers. Furthermore, mRNA levels of IL-17 and IL-8 are correlated with each other and with peripheral neutrophil counts. CONCLUSIONS: Our findings indicate that Th17 cells and their signature cytokine are involved in the process of atherogenesis. These data suggest that Th17 cells link T cell activity with neutrophilic inflammation in atherosclerosis.

[The relationship between reactive oxygen species-dependent activation of p38 MAPK and the expression of tumor necrosis factor-α in cultured cardiomyocytes].

AIM: To investigate the role of p38 mitogen-activated protein kinase(MAPK) in lipopolysaccharide (LPS)-induced tumor necrosis factor-α (TNF-α) expression in neonatal rat cardiomyocytes and to determine the relationship between reactive oxygen species (ROS) and p38 MAPK activation. METHODS: Cardiomyocytes were isolated from neonatal Sprague-Dawley rats and cultured by differential adhesion. Expression of TNF-α was determined in culture medium by ELISA. Activation of p38 MAPK was determined by Western blot analysis with phospho-specific antibody. ROS generation in cardiomyocytes was determined by peroxide specific probe 2', 7'-dichlorofluorescin diacetate (DCF-DA). RESULTS: In cardiomyocytes stimulated with LPS, the content of TNF-α in culture medium correlated with the activity of p38 MAPK in a time-dependent manner. The activation of p38 was observed after stimulation of 1 mg/L LPS for 1 h. TNF-α accumulated significantly in culture medium at 3 h after stimulation of LPS (P<0.05), which was remarkably attenuated by pretreatment with p38 MAPK specific inhibitor SB203580 (P<0.01). Furthermore, the production of ROS in cardiomyocytes stimulated with LPS was also increased at 1 h after stimulation of LPS, consistent with p38 MAPK activity. Pretreatment with antioxidants such as N-acetylcysteine and diphenyleneiodonium significantly inhibited the activation of p38 MAPK compared with LPS control (P<0.05). There was no significance in the activity of p38 MAPK among antioxidants pretreatment and non-LPS control groups. CONCLUSION: The activation of p38 MAPK plays an important role in TNF-α expression in LPS-stimulated cardiomyocytes and the increase of ROS production is prerequisite for the activation of p38 MAPK.

Epicardial ablation of right pulmonary artery ganglionated plexi for the prevention of atrial fibrillation originating in the pulmonary veins.

PROBLEM PRESENTED: A novel study of catheter ablation of the right pulmonary artery ganglionated plexi (RPA GP) to reduce atrial fibrillation (AF) originating in the pulmonary veins (PVs) is presented. STUDIES UNDERTAKEN: In 20 dogs, atrial effective refractory periods (AERPs), PVERP, and the dispersion of AERP (dAERP) were measured at baseline during RPA GP stimulation and after ablation. Programmed stimulation and burst stimulation protocols were performed at 4 distal PVs to measure the percentage of AF induced before and after ablation. RESULTS: Stimulation of the RPA GP shortened AERP (116 +/- 16 vs 130 +/- 10 milliseconds, P < .01) and PVERP (122 +/- 14 vs 136 +/- 12 milliseconds, P < .01), and increased dAERP (31 +/- 6 vs 23 +/- 6 milliseconds, P < .01). However, the above indices revealed an adverse change after excision (AERP, 138 +/- 7 vs 130 +/- 10 milliseconds; PVERP, 146 +/- 18 vs 136 +/- 12 milliseconds; and dAERP, 19 +/- 5 vs 23 +/- 6 milliseconds; P < .05). Furthermore, the percentage of AF induced from PVs was significantly reduced with vagosympathetic stimulation (40% vs 90%, P < .01). CONCLUSIONS: Ablation of the RPA GP changes the electrophysiologic properties of both the atria and the PVs and decreases AF inducibility arising from the PVs.

Caveolin-1 restoration by cholesterol enhances the inhibitory effect of simvastatin on arginine vasopressin-induced cardiac fibroblasts proliferation.

Caveolin-1 (cav1) has been implicated in the regulation of cell growth, and its expression can be regulated by cellular cholesterol content. In this study, we examined the effect of manipulating cellular cholesterol content on cav1 expression and the proliferation of adult rat cardiac fibroblasts (CFs) in the presence of arginine vasopressin (AVP). We found that AVP concentration-dependently down-regulated the expression of cav1 protein. Cav1 antisense treatment enhanced the proliferatory effect of AVP. Simvastatin, a HMG-CoA reductase inhibitor, further down-regulated cav1 protein, whereas repleting cells with cholesterol increased cav1 protein and enhanced the anti-growth effect of simvastatin. Our results provide a novel finding that cholesterol restoration may confer an additional inhibitory effect over simvastatin on AVP-induced CFs proliferation through cholesterol-cav1 interaction.

Silencing GIRK4 expression in human atrial myocytes by adenovirus-delivered small hairpin RNA.

GIRK4 has been shown to be a subunit of I(KACh), and the use of GIRK4 in human atrial myocytes to treat arrhythmia remains an important research pursuit. Adenovirus-delivered small hairpin RNA (shRNA) has been used to mediate gene knockdown in mouse cardiocytes, yet there is no information on the successful application of this technique in human cardiocytes. In the current study, we used a siRNA validation system to select the most efficient sequence for silencing GIRK4. To this end, adenovirus-delivered shRNA, which expresses this sequence, was used to silence GIRK4 expression in human atrial myocytes. Finally, the feasibility, challenges, and results of silencing GIRK4 expression were evaluated by RT-PCR, western blotting, and the voltage-clamp technique. The levels of mRNA and protein were depressed significantly in cells infected by adenovirus-delivered shRNA against GIRK4, approximately 86.3% and 51.1% lower than those cells infected by adenovirus-delivered nonsense shRNA, respectively. At the same time, I(KACh) densities were decreased 53% by adenovirus-delivered shRNA against GIRK4. In summary, adenovirus-delivered shRNA against GIRK4 mediated efficient GIRK4 knockdown in human atrial myocytes and decreased I(KACh) densities. As such, these data indicated that adenovirus-delivered shRNA against GIRK4 is a potential tool for treating arrhythmia.