Research progress in sodium calcium exchanger and heart failure with preserved ejection fraction / 中国临床药理学与治疗学

Sodium calcium exchanger (NCX) is encoded by the SCL8 family genes and belongs to the cation/Ca

Effects of Hyperthyroidism on Contractility and Na+/Ca2+ Exchanger Activity in the Isolated Papillary Muscle of Rats

Abstract Background: Hyperthyroidism (Hy) is an endocrine disorder, in which the thyroid hormones markedly alter the cardiac function. Increased myocardial contractility and cardiac output, improvement in diastolic relaxation, changes in electrical activity, increments in ventricular mass, and arrhythmias have been reported. However, the influences of thyroid hormones upon molecular mechanisms of cardiac functions have not yet been fully understood. Objectives: To evaluate changes in cardiac contractile parameters and the Na+/Ca2+ exchanger (NCX) function in induced hyperthyroid rats. Methods: Hy was induced by intraperitoneal injections of T3 (15 μg/100 g) for 10 days. Contractile parameters and NCX function were evaluated in the isolated papillary muscle. Data normality was confirmed by the Shapiro-Wilk test. The comparison between groups was performed through an unpaired Student's t-test. Results are expressed as mean ± SD. The accepted significance level was p < 0.05. Results: Our data revealed, in the Hy group, an increase of 30.98% in the maximum speed of diastolic relaxation (-284.64 ± 70.70 vs. -217.31 ± 40.30 mN/mm2/sec (p = 0.027)) and a boost of 149% in the NCX function in late phase of relaxation (20.17 ± 7.90 vs. 50.22 ± 11.94 minutes (p = 0.002)), with no changes in the maximum twitch force (p = 0.605) or maximum speed of systolic contraction (p = 0.208) when compared to the control. Conclusion: The improvement in relaxation parameters is hypothetically attributed to an increase in Sarco-Endoplasmic Reticulum Ca2+ATPase isoform 2 (SERCA2) expression and an increased calcium flow through L-type channels that boosted the NCX function.

Inhibition of endotoxin on the function of cardiac sarcoplasmic reticulum in rats / 解放军医学杂志

Objective To observe the enzymatic changes of myocardial sarcoplasmic reticulum in rats after injecting endotoxin (LPS), and provide basic research results for the future study of myocardial sarcoplasmic reticulum dysfunction caused by LPS in rats. Methods Ten SD rats were randomly divided into blank control group and LPS injection group with 5 rats in each group. In the LPS injection group, endotoxin was injected into the tail vessels of the rats. Results The heart rate (HR) of the LPS injection group increased and was faster than that in the blank control group [(204±18) beat per min vs. (139±10) beat per min on the first day, and (199±22) beat per min vs. (143±17) beat per min on the next day, both P values were less than 0.05]. The mean arterial pressure (MAP) was lower than that of the blank control group on the first day [(87±12) mmHg vs. (102±7) mmHg, P<0.05]. Under light and electron microscope, the myocardial cells of rats with LPS injection were loosely arranged, with intercellular infiltration with inflammatory cells, muscle fibers broken, and difficult to identify the morphology of mitochondria and sarcoplasmic reticulum. Quantitative PCR results showed that after endotoxin injection, troponin (CASQ1), sodium-calcium exchanger (NCX), calmodulin phosphatase 1 (ppplCa), phospholipid protein (PLN), sarcoplasmic reticulum Ca2+-ATPase (SERCA2) increased significantly (P<0.05). Conclusion Endotoxin can inhibit cardiomyocyte function by affecting the activity of sarcoplasmic reticulum calcium regulatory protein-related enzymes through various mechanisms.

Progress of relationship between sodium-calcium exchanger 1 and tumors / 肿瘤研究与临床

Sodium-calcium exchanger 1 (NCX1) is a type of two-way translocator with cell membrane structure. It is involved in the transport of Ca2+, regulates a variety of physiological and pathological processes, and is closely related to the growth and metastasis of tumors. This article reviews the progress of the relationship between NCX1 and tumor development.

Progress of relationship between sodium-calcium exchanger 1 and tumors / 肿瘤研究与临床

Sodium-calcium exchanger 1 (NCX1) is a type of two-way translocator with cell membrane structure. It is involved in the transport of Ca2+, regulates a variety of physiological and pathological processes, and is closely related to the growth and metastasis of tumors. This article reviews the progress of the relationship between NCX1 and tumor development.

Effect of atorvastatin on progression of heart failure and association with sodium-calcium exchanger expression / 中国病理生理杂志

[ ABSTRACT] AIM:To investigate the effect of atorvastatin on the development of heart failure after myocardial infarction and the association with sodium-calcium exchanger (NCX) expression.METHODS:The model of heart failure was established by ligation of the anterior descending coronary artery for 8 weeks.The rats were randomly divided into con-trol group, heart failure group, and atorvastatin group.Either atorvastatin (10 mg· kg-1· d-1) or vehicle was orally ad-ministered to the rats on the next day after the surgery .The left ventricular function and NCX expression were analyzed 8 weeks after ligation .Neonatal rat cardiomyocytes were cultured to investigate the effect of atorvastatin on the changes of cal -cium concentration induced by hypoxemia .RESULTS: A decrease in left ventricular diastolic dimension , an increase in left ventricular fractional shortening , and reductions of BNP level and NCX expression were observed in atorvastatin group . The hypoxemia-induced calcium overload in cultured cardiomyocytes was inhibited by atorvastatin , and it was inhibited by the inhibitor of NCX .CONCLUSION:Atorvastatin treatment improves cardiac function , which may be related to the ex-pression and function of sodium calcium exchanger in heart failure .

Effects of dioscin on rat myocardial contractility / 中国药理学通报

Aim To investigate the effects of dioscin ( Dio) on rat myocardial contractility. Methods Left ventricular contractile function was measured using the Langendorff non-recirculating mode of isolated rat heart perfusion. Effects of low, middle and high concentra-tion of Dio were investigated by measuring left ventricu-lar systolic pressure ( LVSP ) and left ventricular end diastolic pressure ( LVEDP) . Also, peak rates of rise/fall of left ventricular pressure ( ± dp/dtmax ) of isolated rat heart were calculated. Effects of Dio on intracellu-lar free calcium concentration in rat H9 c2 cells were measured by using the confocal microscopy. Mitochon-drial membrane potential was detected with multifunc-tional microplate reader. Results With 0. 1, 1 μmol · L-1 Dio, LVSP were significantly enhanced from (11. 55 ± 0. 52), (10. 53 ± 0. 28) kPa to (13. 08 ± 0. 72), (12. 53 ±0. 64) kPa(P<0. 01); +dp/dtmax were dramatically increased from ( 0. 38 ± 0. 10 ) , (0. 40 ± 0. 07) kPa·ms-1 to (0. 42 ± 0. 11), (0. 43 ± 0. 02) kPa·ms-1(P<0. 05). With the 10μmol· L-1 Dio, LVSP and + dp/dtmax were both decreased from (12. 13 ± 0. 33) kPa and (0. 42 ± 0. 04) kPa· ms-1 to ( 9. 46 ± 0. 77 ) kPa and ( 0. 24 ± 0. 04 ) kPa ·ms-1 (P <0. 01). With 0. 1, 1, 10 μmol·L-1 Dio, the relative fluorescence intensity of intracellular free calcium concentrations was increased significantly from (16. 62 ± 0. 89) to (21. 48 ± 0. 80), (25. 68 ± 0. 69) and (19. 84 ± 0. 66)(P <0. 01)respectively. 0. 1, 1μmol·L-1 Dio showed no significant effects on the mitochondrial membrane potential of rat H9 c2 cells, while with effects of 10 μmol·L-1 Dio, the ra-tio of JC-1 monomer and J-aggregates was changed from (1. 14 ± 0. 03) to (1. 35 ± 0. 06)(P<0. 01), indica-ting a decrease in the mitochondrial membrane poten-tial. Conclusion Low and middle concentrations of Dio show a positive inotropic effect on isolated rat heart, as the LVSP and + dp/dtmax are enhanced, which may concern with the increase of the intracellu-lar concentration of Ca2+. It will not cause the calcium overload while the intracellular concentration of Ca2+ is increased by low and middle concentration of Dio in the myocytes except high concentration of Dio.

Sodium-calcium exchanger promoter promotes differentiation of mouse induced pluripotent stem cells into cardiomyocytesin vitro / 中国组织工程研究

BACKGROUND:Inducing pluripotent stem cels has been considered as a promising treatment for ischemic heart disease. However, an ideal inducing method has not been found yet. OBJECTIVE:To investigate the role of sodium-calcium exchanger (NCX1) promoter in the differentiation of mouse induced pluriptent stem cels (miPS) into cardiomyocytes. METHODS: The pLVX-IRES-ZsGreen1 vectors which contain NCX1 promoter constructed by recombinant DNA technology were co-transfected to 293FT cels with ViraPowerTM Lentiviral Packaging Mix. The recombinant lentiviruses infected with miPS were selected and purified by puromycin. miPS were recovered and passaged to form embryoid bodies. The embryoid bodies were induced by differentiation medium containing various concentrations of the virus titer. The number of beating embryoid bodies were calculated. The expression profiles of the myocardial intra-markers were tested to determine the differentiation efficiency of iPSC by RT-PCR and immunofluorescence analysis. RESULTS AND CONCLUSION:pLVX-IRES-ZsGreen1 vectors which contain NCX1 promoter were constructed and confirmed by PCR. Virus could be packaged, purified and concentrated successfuly. The recombinant lentivirus to transduce miPS was sorted by flow cytometry. In contrast to NCX1-/GFP- cels, NCX1+/GFP+ cels were differentiated and developed prominent beating areas with sustained contractile activity for additional 4 days, and demonstrated positive expression of gap communication marker CX43 and cardiac troponin. The expressions of GATA4, MEF2c and Nkx2.5 in the NCX1+ cels were 4.2, 7.5, and 2.5 times those in NCX1- cels. Results showed the NCX1 promoter can promote the cardiac differentiation of miPS .

Na+-Ca2+ exchanger modulates Ca2+ content in intracellular Ca2+ stores in rat osteoblasts

Na+ -Ca2+ exchanger (NCX) transports Ca2+ coupled with Na+ across the plasma membrane in a bi-directional mode. Ca2+ flux via NCX mediates osteogenic processes, such as formation of extracellular matrix proteins and bone nodules. However, it is not clearly understood how the NCX regulates cellular Ca2+ movements in osteogenic processes. In this study, the role of NCX in modulating Ca2+ content of intracellular stores ([Ca2+](ER)) was investigated by measuring intracellular Ca2+ activity in isolated rat osteoblasts. Removal of extracellular Na+ elicited a transient increase of intracellular Ca2+ concentration ([Ca2+](i)). Pretreatment of antisense oligodeoxynucleotide (AS) against NCX depressed this transient Ca2+ rise and raised the basal level of [Ca2+](i). In AS-pretreated cells, the expression and activity of alkaline phosphatase (ALP), an osteogenic marker, were decreased. However, the cell viability was not affected by AS-pretreatment. Suppression of NCX activity by the AS-pretreatment decreased ATP-activated Ca2+ release from intracellular stores and significantly enhanced Ca2+ influx via store operated calcium influx (SOCI), compared to those of S-pretreated or control cells. These results strongly suggest that NCX has a regulatory role in cellular Ca2+ pathways in osteoblasts by modulating intracellular Ca2+ content.

Effect of sodium-calcium exchanger and its inhibitors on arrhythmia / 中国临床药理学与治疗学

In cardiomyocytes,sodium-calcium exchanger(NCX) is regarded to play an important role in the regulation of intracellular Ca~(2+) concentration.During the cardiac ischemia/reperfusion or cardenolide intoxication,the inflow Ca~(2+) through NCX reverse mode induce calcium overload and arrhythmia.Recently,the benzyloxyphenyl derivatives have been developed as selective NCX inhibitors,which may have therapeutic potential as a new remedy for arrhythmias.

Effect of valsartan on calcium channel current and sodium-calcium exchanger current in heart failure rats / 中国病理生理杂志

AIM: To determine the effects of valsartan on calcium channel and sodium-calcium exchanger current in isolated ventricular myocytes of congestive heart failure (CHF) rats. METHODS: Eight weeks after coronary ligation, the rats with heart failure were confirmed by measuring the hemodynamic parameters and divided randomly into the group treating with valsartan (CHF-T, 20 mg/kg) and placebo (CHF-C). Sham-operated group rats served as negative controls (PS). Twelve weeks later, 6 rats were selected randomly for the study of ion channel. Single ventricular myocytes of rats were isolated by enzymatic dissociation. The whole-cell patch-clamp recording technique was used to record calcium channel current and sodium-calcium exchanger current. RESULTS: (1) In the hemodynamic variables, HR and blood pressure were not significantly different in three groups. Compared CHF-C with PS group, LVEDP and Cm increased, LVSP and ?d p /d t max decreased ( P 0 05). (4) Na +-Ca 2+ exchanger current in CHF-C group increased significantly. Na +-Ca 2+ exchanger current in CHF-T group was smaller significantly than that in CHF-C group. However, CHF-T group and PS group were not significantly different. CONCLUSION: Administration of valsartan is effective in preventing from cardiac function deterioration, increases calcium channel current and decreases Na +-Ca 2+ exchanger current in ventricular myocytes of heat failure rats.