Effects of apelin-13 on transient sodium currents in rat ischemic ventricular myocardial cells

AIM：To investigate the effects of apelin on ventricular arrythmias and cardiac functions in rat Langendorff perfusion-simulated myocardial ischemia model by observing the changes of transient sodium currents (INa) in normal cells and the simulated ischemic cells in rat left ventricle. METHODS：Ventricular cells were enzymatically isolated by the Langendorff perfusion system. INa was recorded by the technique of whole-cell patch-clamp. Some elements in the extracellular fluid were changed to simulate the normal or ischemic status. Forty Wistar rats were divided into 4 groups：normal group, ischemic group, normal with apelin group and ischemic with apelin group. The effect of apelin-13 on INa was observed. The method of rat Langendorff perfusion was used to simulate the ischemic heart model. The ventricular arrhythmia scores and heart functional parameters were compared. The expression level of sodium channel protein,type V,alpha subunit (SCN5A) in ventricular ischemic cells was measured by Western blotting. RESULTS： Apelin-13 increased INa amplitude in both normal myocardial cells ［(-86±13） pA/pF］ and ischemic myocardial cells ［(-52±15） pA/pF］. The results of current-voltage curve analysis indicated that apelin-13 did not change the conduction velocity of INa in the 4 groups ［(3.2±0.2） pS/pF, （3.1±0.3） pS/pF,（2.9±0.1）pS/pF and （2.8±0.4） pS/pF,respectively, P>0.05］. The membrane potentials at 50% maximal activation in the 4 groups were （-21.9±0.6） mV, （-28.7±0.3） mV, （-30.5±0.7） mV and （-36.8±0.2） mV, respectively, and the slope of activation curves was 5.6±0.3, 5.1±0.4, 4.3±0.3 and 4.9±0.6 (P>0.05), respectively. No difference of ventricular arrhythmia scores between normal group and normal with apelin group, as well as between ischemic group and ischemic with apelin group was observed. LVEDP in normal with apelin group was lower than that in normal group.The dp/dtmax and dp/dtmin in normal with apelin group were higher than those in normal group. Apelin improved cardiac function parameters in the ischemic hearts. The expression of SCN5A was not affected by apelin (28.8±3.6, 29.4±4.1, 30.1±2.9 and 31.3±3.8,respectively,P>0.05). CONCLUSION：Apelin-13 changes the gating properties of sodium channel, enhances the peak INa and facilitates the opening of sodium channel without inducing ventricular arrhythmias. Apelin-13 has a positive inotropic effect on both normal and ischemic hearts.     

Role of canonical transient receptor potential and inflammation in left ventricular fibrosis induced by high salt in Wistar rats

AIM:To explore the role of transient receptor potential channels subfamily C (TRPCs) and inflammation in left ventricular fibrosis induced by high salt and the effect of telmisartan. METHODS:Wistar rats were randomly divided into 3 groups: normal control (C) group (n=13), high salt (8%) model group (HS, n=24) and high salt+telmisartan (T) group (n=12). Tail-cuff artery pressure was determined every 2 weeks. The interstitial collagen deposition and inflammation were observed by Masson and HE staining, respectively. The expression of TRPC1, TRPC3, TRPC6, calcineurin (CaN), nuclear factor-κB p65 (NF-κB p65), transforming growth factor β1 (TGF-β1), interleukin-1β (IL-1β), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1) and monocyte chemoattractant protein-1 (MCP-1) were determined by real-time PCR or Western blotting. RESULTS:Masson staining showed that left ventricle in HS group exhibited severer myocardial interstitial fibrosis compared with C group. TRPC, CaN and NF-κB assays showed that high-salt diet increased the protein expression of TRPC1, TRPC3 and TRPC6, and activated CaN and NF-κB as compared with C group. The results of HE staining, real-time PCR and Western blotting showed that high salt-treated Wistar rats had enhanced cardiac infiltration of inflammatory cells, as well as increased cardiac levels of proinflammatory cytokines (TGF-β1, IL-1β, VCAM-1, ICAM-1 and MCP-1) as compared with C group. After treated with telmisartan, left ventricular mass index and collagen volume fraction became much lower, and the levels of TRPC1, TRPC3, TRPC6, CaN, NF-κB p65, TGF-β1, ICAM-1 and MCP-1 were significantly reduced. CONCLUSION: Inflammation is exacerbated in left ventricular fibrosis induced by high salt. The mechanism may be related to the up-regulation of TRPCs, CaN and NF-κB at mRNA and protein levels. Telmisartan inhibits the expression of TRPCs and NF-κB, and ameliorates the inflammatory responses in left ventricular fibrosis.     

弧底梯形渠的冻胀试验研究

混凝土衬砌弧底梯形渠道具有较好的抗冻胀性能,在我国北方大、中型防渗衬砌渠道中广泛应用,为了进一步探索衬砌厚度与冻胀变形的规律,在工程现场进行了不同工况的试验,总结了衬砌厚度与冻胀变形的规律,并应用价值工程理论对其技术经济指标进行了分析。     

用于梯形渠道的仿翼形便携式量水槽水力性能

机翼形量水设施水力条件优、量水精度高,但翼形曲线的复杂性制约其推广,为此,该研究基于结构简单的仿翼形便携式量水槽,探究其在末级梯形渠道的适用性。模型试验设计5组收缩比、7组流量进行水力性能试验,在此基础上,基于FLOW-3D软件对比分析仿翼形与机翼形量水槽水力性能的差异,深入研究不同收缩比对仿翼形量水槽水力性能的影响。研究结果表明：数值模拟与试验结果的水深数据吻合,误差小于4.91%,数值模拟的方法准确可靠;简化后未改变机翼形过流顺畅、雍水高度小等特点;所有工况上游佛汝德数均小于0.5,雍水高度小于7.6 cm,满足测流精度和渠道安全的要求,收缩比在0.60～0.64范围时,量水槽水力性能最优;基于能量方程及临界流原理建立的流量公式精度较高,平均测流误差为2.75%。该研究表明仿翼形保持了原机翼形良好的水力性能,测流精度高且曲线形式简单,便于推广,对于促进灌区末级梯形渠道便携式量水槽的推广具有实用价值。     

人力资本积累、信息约束与外出务工者返乡创业——基于安徽省993份调研数据的分析

基于2018年安徽省993份问卷调查数据,运用Probit模型实证分析人力资本积累对外出务工者返乡创业的影响。结果表明：文化程度、创业培训以及健康状况对返乡创业具有显著的正向影响,另外,宏观政策环境和信息渠道是影响返乡创业的外在约束条件。因此,应多途径合力提高返乡人员的文化素质,全方位提升创新创业培训的实际成效,强化全体返乡创业者对身体健康的深刻认识,促进实用性创业信息的流动共享。     

梯形渠道跌水口量水的试验研究

跌水是一种较为常见的渠系建筑物,当水流经过跌水口时必然产生缓流向急流的过渡。在梯形渠道上通过2种不同的连接渐变段(扭面与隔墙)以及不同的堰厚和缺口宽度组合,进行了系统的跌水口量水试验,应用量纲分析法建立了2种连接渐变段在不同堰厚下的流量公式,得出流量计算的平均相对误差最大值为3.002%。     

盐胁迫对不同小麦品种NSCCs吸钾作用的影响

根据植物对钾的吸收主要通过钾的专性通道和非选择性阳离子通道(NSCCs)2种途径的钾吸收转运机制,利用钾专性通道抑制剂,研究3个耐盐能力不同的小麦品种在盐胁迫下通过NSCCs转移钾的贡献.结果表明:3个小麦品种根系通过NSCCs的钾转移均受到Na~+的影响,耐盐性最强的小麦品种.其通过NSCCs的钾吸收作用受到的影响较小,对盐最敏感的小麦品种受影响最大,其NSCCs对K~+的吸收受到明显抑制,吸钾贡献率大幅下降.     

Effects of thyroid hormone on myocardial T-type calcium channels at mRNA and protein levels in rats

AIM: To observe the effect of thyroxine on the expression of T-type calcium channels Cav3.1, Cav3.2 and Cav3.3 in rat myocardium, and to explore the possible biological mechanism between the changes of the expression of T-type calcium channels and the arrhythmia in hyperthyroid heart disease. METHODS: Healthy SD rats (n=20) were randomly divided into normal control group (n=10) and hyperthyroid heart disease group (n=10). The animal model was established by intraperitoneal injection of levothyroxine for 35 d. The contents of T3 and T4 in serum, the heart-to-body weight ratio, the diameter of cardiac myocytes and electrocardiograph were measured to evaluate hyperthyroid heart disease. Moreover, the mRNA and protein expression levels of T-type calcium channels in the myocardium were measured by RT-PCR, immunohistochemistry and Western blot. RESULTS: After intraperitoneal injection of levothyroxine for 35 d, compared with the normal control group, the serum contents of T3 and T4, the heart-to-body weight ratio and the diameter of cardiac myocytes were significantly increased in hyperthyroid heart disease group (P<0.05), and arrhythmia occurred in hyperthyroid heart disease group. By immunohistochemistry and Western blot, the protein expression of Cav3.1 increased significantly (P<0.05), while the protein expression of Cav3.2 decreased significantly (P<0.01). However, no change of the Cav3.3 protein was observed. The results of RT-PCR were the same as immunohistochemistry and Western blot. CONCLUSION: Thyroxine promotes the expression of Cav3.1 in the myocardium but inhibits the expression of Cav3.2 at mRNA and protein levels, which might be involved in arrhythmia in hyperthyroid heart disease.     

八脉及其交会穴位在宠物临床上的应用

八脉有督脉、任脉、冲脉、带脉、阴维脉、阳维脉、阴跷脉、阳跷脉,是别行奇道的经脉,具有统摄经脉气血、协调阴阳的作用。任督二脉穴位主治范围广泛,六条奇经虽无本经专属经穴,但其纵横交叉于十二经脉之间,往往一脉通多经。运用比较针灸方法,借鉴中医临床的研究成果和成熟经验,找寻出对某些疾病有特效的奇经八脉穴位/交会穴位,可扩大正经的主治范围,提高针灸的施治效果,以更好地防治犬、猫疾病。