Stilbene disulfonates block ATP-sensitive K+ channels in guinea pig ventricular myocytes

Effects of stilbene disulfonates on single K_ATP channel currents were investigated in inside-out and outside-out membrane patches from guinea pig ventricular myocytes. All drugs tested, 4,4′-diisothiocyanatostilbene, 2,2′-disulfonic acid (DIDS), 4-acetamido0-4′-isothiocyanatostilbene-2,2′-disulfonic acid (SITS), 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNDS), and 4,4′-diaminostilbene-2,2′-disulfonic acid (DADS), inhibited the K_ATP channel when they were applied to the intracellular, but not extracellular side of the membrane patch. Inhibitory actions of DIDS and SITS were irreversible, whereas those induced by DNDS and DADS were reversible. K_ATP channel inhibition was concentration dependent with an order of potency of DIDS>SITS ≈ DNDS > DADS; the Hill coefficient was close to unity for each drug. No change in channel conductance was observed during exposure to DIDS or DNDS; however, channel kinetics was altered. Distribution of the open time within bursts and that between bursts could be described by a single exponential relation in the absence and presence of DIDS or DNDS. The time constant of the open time within bursts was not altered, but that between bursts was decreased by DIDS (from 40.0±8.1 to 29.8±6.7 msec, P< 0.05) and by DNDS (from 43.1±9.3 to 31.9±7.1 msec, P<0.05). Distributions of closed time within bursts were also fitted to a single exponential function both in the absence and presence of drugs, while those of the closed time between bursts were fitted to a single exponential function in the absence of drugs, but a double exponential function was required in the presence of drugs. The rates of onset and development of channel inhibition by DIDS and DNDS appeared to be concentration dependent; a longer time was required to reach a new steady-state of channel activity as drug concentration was decreased. Inhibition by DIDS or DNDS was regulated by intracellular pH; inhibition was greater during acidic conditions. For DIDS (0.1 mm), the open probability (P _o) expressed as a fraction of the value before drug application was 42.9±8.3% at pH 7.4 and 8.2±6.6% at pH 6.5 (P<0.01); corresponding values for DNDS (1 mm) were 39.6±17.6 and 8.9 ±5.8%, respectively (P<0.01). From these data, we conclude that stilbene disulfonates block the K_ATP channel by binding to their target site with one-to-one stoichiometry. Similar to glibenclamide, the binding of stilbene disulfonates may reflect interpolation in an “intermediate lipid compartment” between the cytosolic drug and the site of drug action.     

血浆成纤维细胞激活蛋白含量在心肌梗死围手术期的临床意义

摘要 目的：明确血浆成纤维细胞激活蛋白（fibroblast activation protein,FAP）含量在心肌梗死患者围手术期的临床意义。方法：选取2021年11月至2022年4月入院接受经皮冠状动脉介入治疗（percutaneous coronary intervention,PCI）治疗的心肌梗死患者15例,年龄和性别匹配的健康者17例以及作为对照组。收集其血浆样本和影像学及其他相关临床资料,采用酶联免疫吸附法（enzyme linked immunosorbent assay,ELISA）测定循环血FAP的含量。并用配对t检验等统计学方法对其进行分析。结果：心肌梗死组循环血FAP的浓度为107.3±3.472 ng/mL,低于对照组（117.9±2.533 ng/mL）,差异具有统计学意义（P<0.01）。心肌梗死组与对照组比较,其一般资料除cTnT外（P<0.01）无明显差异。心肌梗死患者循环血FAP水平在PCI术后显著下降,差异具有统计学意义（P<0.01）。PET-磁共振（PET-MR）检测结果显示心肌纤维化活跃程度较PCI术后初期明显降低。结论：心肌梗死患者PCI围手术期的血浆FAP水平与心肌纤维化的活跃程度有关。血浆FAP水平的变化曲线可为心肌梗死患者预后恢复的诊断提供参考依据。     

A thrombocyte-induced myocardial dysfunction in the ischemic and reperfused guinea pig heart is mediated by reactive oxygen species

In recent investigations, we could demonstrate that thrombocytes are able to contribute to ischemia- and reperfusion-induced injury of the heart. The aim of the current study was to investigate whether reactive oxygen species are responsible for induction of myocardial dysfunction under these conditions. Isolated, perfused, and pressure-volume work–performing guinea pig hearts were exposed to a 30-min low-flow ischemia (1 ml/min) and were reperfused (5 ml/min). Washed, homologous blood platelets were administered as a 1-min bolus (20,000 per microliter of perfusion buffer), either during the 15th minute of ischemia or in the first or fifth minute of reperfusion in the presence of thrombin (0.3 U/ml perfusion buffer)). The radical scavengers superoxide dismutase (SOD; 10 U/ml perfusate) and catalase (30 U/ml perfusate) were added during ischemia or in the first or fifth minute of reperfusion, respectively. Intracoronary platelet retention (in percentage of platelets applied) and recovery of EHW (postischemic EHW in percentage of preischemic EHW) were quantified. Ischemic and reperfused hearts with time-matched application of platelets but without administration of SOD or catalase served as controls. Interestingly, both administration of SOD during ischemia and in reperfusion significantly improved recovery of EHW (88.4 ± 2%, 82.6 ± 1%, and 90 ± 3%, respectively) as compared with the case of controls (56.2 ± 3%, 42 ± 2%, and 75 ± 2%, respectively). Platelet retention, however, was not significantly influenced by administration of SOD during ischemia or reperfusion (26 ± 2%, 31 ± 2%, and 26 ± 2%) compared with controls (30.5 ± 3%, 33 ± 2%, and 22 ± 3%, respectively). Coadministration of catalase, on the other hand, exhibited some cardioprotective potential only in the first minute of reperfusion (recovery, 61% ± 4%) as compared with the case of control (42 ± 2%). We conclude that thrombocytes under conditions of ischemia and reperfusion are able to induce a myocardial dysfunction mediated by reactive oxygen species. Superoxide seems to play a major role in this respect.     

Incessant tachycardia in a patient with advanced heart failure and left ventricular assist device: What is the mechanism?

We present a case of incessant wide-complex tachycardia in a patient with left-ventricular assist device, and discuss the differential diagnosis with an in-depth analysis of the intracardiac tracings during the invasive electrophysiologic study, including interpretation of the relative timing of the fascicular signals during tachycardia and in sinus rhythm, and interpretation of pacing and entrainment maneuvers.     

Proton or photon radiosurgery for cardiac ablation of ventricular tachycardia? Breath and ECG gated robust optimization

PurposeVentricular tachycardia (VT) is a life-threatening heart disorder. The aim of this preliminary study is to assess the feasibility of stereotactic body radiation therapy (SBRT) photon and proton therapy (PT) plans for the treatment of VT, adopting robust optimization technique for both irradiation techniques.MethodsECG gated CT images (in breath hold) were acquired for one patient. Conventional planning target volume (PTV) and robust optimized plans (25GyE in single fraction) were simulated for both photon (IMRT, 5 and 9 beams) and proton (SFO, 2 beams) plans. Robust optimized plans were obtained both for protons and photons considering in the optimization setup errors (5 mm in the three orthogonal directions), range (±3.5%) and the clinical target volume (CTV) motion due to heartbeat and breath-hold variability.ResultsThe photon robust optimization method, compared to PTV-based plans, showed a reduction in the average dose to the heart by about 25%; robust optimization allowed also reducing the mean dose to the left lung from 3.4. to 2.8 Gy for 9-beams configuration and from 4.1 to 2.9 Gy for 5-beams configuration. Robust optimization with protons, allowed further reducing the OAR doses: average dose to the heart and to the left lung decreased from 7.3 Gy to 5.2 GyE and from 2.9 Gy to 2.2 GyE, respectively.ConclusionsOur study demonstrates the importance of the optimization technique adopted in the treatment planning system for VT treatment. It has been shown that robust optimization can significantly reduce the dose to healthy cardiac tissues and that PT further increases this gain.     

Cardiac disease modeling using induced pluripotent stem cell-derived human cardiomyocytes

Causative mutations and variants associated with cardiac diseases have been found in genes encoding cardiac ion channels, accessory proteins, cytoskeletal components, junctional proteins, and signaling molecules. In most cases the functional evaluation of the genetic alterationhas been carried out by expressing the mutated proteins in in-vitro heterologous systems. While these studies have provided a wealth of functional details that have greatly enhanced the understanding of the pathological mechanisms, it has always been clear that heterologous expression of the mutant protein bears the intrinsic limitation of the lack of a proper intracellular environment and the lack of pathological remodeling. The results obtained from the application of the next generation sequencing technique to patients suffering from cardiac diseases have identified several loci, mostly in non-coding DNA regions, which still await functional analysis. The isolation and culture of human embryonic stem cells has initially provided a constant source of cells from which cardiomyocytes(CMs) can be obtained by differentiation. Furthermore, the possibility to reprogram cellular fate to a pluripotent state, has opened this process to the study of genetic diseases. Thus induced pluripotent stem cells(i PSCs) represent a completely new cellular model that overcomes the limitations of heterologous studies. Importantly, due to the possibility to keep spontaneously beating CMs in culture for several months, during which they show a certain degree of maturation/aging, this approach will also provide a system in which to address the effect of long-term expression of the mutated proteins or any other DNA mutation, in terms of electrophysiological remodeling. Moreover, since i PSC preserve the entire patients’ genetic context, the system will help the physicians in identifying the most appropriate pharmacological intervention to correct the functional alteration. This article summarizes the current knowledge of cardiac genetic diseases modelled with i PSC.     

The effect of disease on human cardiac protein expression profiles in paired samples from right and left ventricles

Background

Cardiac diseases (e.g. coronary and valve) are associated with ventricular cellular remodeling. However, ventricular biopsies from left and right ventricles from patients with different pathologies are rare and thus little is known about disease-induced cellular remodeling in both sides of the heart and between different diseases. We hypothesized that the protein expression profiles between right and left ventricles of patients with aortic valve stenosis (AVS) and patients with coronary artery disease (CAD) are different and that the protein profile is different between the two diseases. Left and right ventricular biopsies were collected from patients with either CAD or AVS. The biopsies were processed for proteomic analysis using isobaric tandem mass tagging and analyzed by reverse phase nano-LC-MS/MS. Western blot for selected proteins showed strong correlation with proteomic analysis.

Results

Proteomic analysis between ventricles of the same disease (intra-disease) and between ventricles of different diseases (inter-disease) identified more than 500 proteins detected in all relevant ventricular biopsies. Comparison between ventricles and disease state was focused on proteins with relatively high fold (±1.2 fold difference) and significant (P < 0.05) differences. Intra-disease protein expression differences between left and right ventricles were largely structural for AVS patients and largely signaling/metabolism for CAD. Proteins commonly associated with hypertrophy were also different in the AVS group but with lower fold difference. Inter-disease differences between left ventricles of AVS and CAD were detected in 9 proteins. However, inter-disease differences between the right ventricles of CAD and AVS patients were associated with differences in 73 proteins. The majority of proteins which had a significant difference in one ventricle compared to the other pathology also had a similar trend in the adjacent ventricle.

Conclusions

This work demonstrates for the first time that left and right ventricles have a different proteome and that the difference is dependent on the type of disease. Inter-disease differential expression was more prominent for right ventricles. The finding that a protein change in one ventricle was often associated with a similar trend in the adjacent ventricle for a large number of proteins suggests cross-talk proteome remodeling between adjacent ventricles.     

心脏室间隔起搏与右室心尖部起搏对心功能的影响

目的:探讨右心室间隔部(Right Ventricular Septum,RVS)起搏和右心室心尖部(Rightventricularape,RVA)起搏对心功能的影响,为临床提供参考.方法:采用前瞻性研究的方法,对我院自2008年8月-2011年8月收治的行起搏器治疗的72例患者随机均分为实验组和对照组,实验组采用RVS起搏,对照组采用RVA起搏,比较植入后15分钟和1年后测定两组间心室起搏参数差异及血流动力学参数左室射血分数(LVED、每搏量(sv)、心脏指数(CD、二尖瓣血流E峰和A峰最大充盈速度比值(E/A)差异.结果:植入后15分钟和1年后,实验组和对照组起搏参数起搏阈值、电极阻抗、心腔内R波幅度进行比较,差异无统计学意义(P＞0.05).植入后1年后,两组间的血流动力学参数比较,差异有统计学意义(P＜0.05).结论:RVS起搏优于RVA起搏,有望替代传统的右心室心尖部成为最佳的心室起搏部位.     

Protection against in vivo focal myocardial ischemia/reperfusion injury-induced arrhythmias and apoptosis by Hesperidin

Among the heart diseases, ischemia and reperfusion (I/R) induced arrhythmias contribute to episodes of sudden death. Cardiac arrhythmias during ischemia reperfusion are believed to be related to oxidative stress. Therefore, the aim of this study was to examine whether treatment with Hesperidin alleviates arrhythmias and infarct size in experimentally-induced myocardial I/R injury using an in vivo rat model. In this study haemodynamics parameters, markers of inflammation, biomarkers of oxidative stress and tissue nitrite level and infarct size of the heart were estimated in various groups. I/R showed a significant decrease in tissue nitrite and antioxidant level and significant increase in arrhythmias, inflammation and myocardial cell apoptosis. Treatment with Hesperidin showed a significant increase in tissue nitrite, antioxidant level and reduction in inflammation, arrhythmias and apoptosis. In conclusion, the protecting effect of Hesperidin in I/R induced arrhythmias is due to reduction in inflammation and oxidative stress.