Effect of suppressing calcium-sensing receptor on rat myocardial H9c2 cell hypertrophy induced by angiotensin Ⅱ / 中华地方病学杂志

Objective To explore the effects and possible mechanism of calcium-sensing receptor(CaSR) in rat myocardial H9c2 cells hypertrophy model using angiotensin Ⅱ (Ang Ⅱ).Methods Cardiac hypertrophy model was established by treating cultured H9c2 cells with Ang Ⅱ in vitro.Hypertrophic H9c2 cells were treated with gadolinium chloride (GdCl3,a specific agonist of CaSR) and/or with Calhex231 (a specific inhibitor of CaSR) and 3-methyladenine (3-MA,a specific inhibitor of autophagy) to divided into 5 groups (six in each group):control,Ang Ⅱ,GdCl3 + Ang lⅡ,GdCl3 + Calhex231 + Ang Ⅱ,GdCl3 + 3-MA + Ang Ⅱ groups.To evaluate the status of H9c2 cells hypertrophy,protein content was determined through a coomassie brilliant blue protein kit and the expression of Ca2+/calmodulin-dependent protein kinase Ⅱ (CaMK Ⅱ) and the phosphorylation form (pCaMK Ⅱ/CaMK Ⅱ) was analyzed by Western blotting.The protein expression of CaSR,autophagy maker [Beclin-1,micmtubule-associated protein 1 light chain 3(LC3)Ⅱ/LC3 Ⅰ,P62] and Ca2+/calmodulin-dependent-protein kinase-kinase-β (CaMKKβ)-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) pathway was analyzed by Western blotting.Results ①GdCl3 further increased H9c2 cells protein content [control group:(2.52 ± 0.84) g/L,Ang Ⅱ group:(8.72 ± 3.60) g/L GdCl3 + Ang Ⅱ group:(14.17 ± 4.49) g/L,all P ＜ 0.05] and the expression of CaSR (control group:0.22 ± 0.04,Ang Ⅱ group:0.43 ± 0.02,GdCl3 + Ang Ⅱ group:0.63 ± 0.08,all P ＜ 0.05) and pCaMK Ⅱ/CaMKⅡ (control group:0.25 ± 0.05,AngⅡ group:0.51 ± 0.03,GdCl3 + AngⅡ group:0.77 ± 0.06,all P＜ 0.05) induced by Ang Ⅱ.Calhex231 suppressed the increasing of hypertrophy indicators induced by GdCl3 [GdCl3 + Calhex231 + AngⅡ group,CaSR:0.41 ± 0.16,protein content:(9.92 ± 2.54) g/L,pCaMK Ⅱ/CaMKⅡ:0.58 ± 0.08,all P ＜ 0.05].②GdCl3 promoted the effect of Ang Ⅱ in regulation of autophagy such as Beclin-1 protein increased (control group:0.31 ± 0.06,AngⅡ group:0.55 ± 0.09,GdCl3 + AngⅡ group:0.74 ± 0.08,all P ＜ 0.05),LC3 Ⅱ/LC3 Ⅰ increased (control group:0.28 ± 0.06,Ang Ⅱ group:0.56 ± 0.10,GdCl3 + Ang Ⅱ group:1.00 ± 0.15,all P ＜ 0.05) and P62 protein decreased (control group:0.54 ± 0.03,AngⅡ group:0.34 ± 0.02,GdCl3 + AngⅡ group:0.15 ± 0.03,all P ＜ 0.05).Moreover,Calhex231 suppressed autophagy induced by GdCl3 (GdCl3 + Calhex231 + Ang Ⅱ group,Beclin-1:0.53 ± 0.14,LC3 Ⅱ/LC3 Ⅰ:0.57 ± 0.12,P62:0.28 ± 0.05,all P ＜ 0.05).③GdCl3 increased pCaMKKβ/CaMKKβ (control group:0.43 ± 0.09,AngⅡ group:0.76 ± 0.12,GdCl3 + AngⅡ group:1.19 ± 0.21,all P ＜ 0.05),pAMPK/AMPK (control group:0.38 ± 0.11,AngⅡ group:0.68 ± 0.08,GdCl3 + AngⅡ group:1.18 ± 0.08,all P ＜ 0.05) and decreased pmTOR/mTOR (control group:0.90 ± 0.10,Ang Ⅱ group:0.54 ± 0.04,GdCl3 + AngⅡ group:0.29 ± 0.09,all P ＜ 0.05).Furthermore,Calhex231 blocked the effect of GdCl3 on the above-mentioned proteins changes (GdCl3 + Calhex231 + Ang Ⅱ group,pCaMKKβ/CaMKKβ:0.75 ± 0.06,pAMPK/AMPK:0.57 ± 0.05,pmTOR/mTOR:0.51 ± 0.08,all P ＜ 0.05).Conclusion Inhibiting calcium-sensing receptor expression has reversed H9c2 cell hypertrophy induced by Ang Ⅱ,which may be related to suppressing autophagy and suppressing CaMKKβ-AMPK-mTOR pathway.

Effects and mechanisms of low concentration dopamine on hydrogen peroxide-induced apoptosis in cultured neonatal rat cardiomyocytes / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To study the effects of low concentration dopamine(DA) on hydrogen peroxide-induced apoptosis in cultured rat cardiomyocytes as well as the possible molecular mechanisms.</p><p><b>METHODS</b>Cultured neonatal rat cardiomyocytes were randomly divided into the following groups: control group (control), hydrogen peroxide group (H2O2), pretreated with low concentration dopamine ( DA + H2O2), dopamine receptor l(DR1) antagonist group (DR1 + DA + H2O2), dopamine receptor 2(DR2) antagonist group (DR2 + DA + H2O2). The cell apoptosis was then assessed by MTT and flow cytometry. The cellular ultrastructure changes were observed by transmission electron micro- scope. The activity of lactate dehydrogenase(LDH )and superoxide dismutase (SOD) in cell medium was analyzed by colorimetry. The protein expressions of Cytochrone c, Caspase 3 and Caspase 9 were obtained by Western blot.</p><p><b>RESULTS</b>Compared with hydrogen peroxide group, low concentration dopamine(10 µmol/L) decreased the apoptosis rate and the expression of protein of apoptosis related protein, enhanced SOD activity, decreased LDH activity. DR1 antagonist SCH-23390 treatment inhibited dopamine induced cardiac protective effect. DR2 antagonist haloperido treatment had no changes compared with dopamine group.</p><p><b>CONCLUSION</b>Above findings indicate that low concentration dopanine inhibits apoptosis induced by hydrogen peroxide in neonatal rat cardiomyocytes, which is partly associated with the activation of DR1.</p>

Association between calcium-sensing receptor protein expression and rat cardiomyocyte apoptosis / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the relationship between calcium-sensing receptor protein (CaSR) expression and rat cardiomyocyte apoptosis and related signal transduction pathways.</p><p><b>METHODS</b>The CaSR, BCl2, Caspase3 protein and ERK1/2 phosphorylation or non-phosphorylation were detected by Western blot. Cardiomyocyte apoptosis was detected by flow cytometry and immunofluorescence.</p><p><b>RESULTS</b>CaSR protein was detected in rat cardiac tissue and CaSR activator gadolinium (GdCl3) induced cardiomyocyte apoptosis and increased ERK1/2 phosphorylation and expression of BCl2 and activated Caspase3. The selective mitogen-activated protein kinase (MAPK) inhibitor PD98059 abolished gadolinium -induced ERK1/2 activation and BCl2 expression, further increased the activation of Caspase3 and cardiomyocyte apoptosis.</p><p><b>CONCLUSION</b>Our results demonstrate the CaSR existence in cardiomyocytes and CaSR activation by gadolinium can induce myocyte apoptosis by activating Caspase3 and tyrosine protein kinase pathway.</p>

Expression of calcium-sensing receptor in the rat cardiac tissue at different age and its relation with anoxia-reperfusion injury / 中国病理生理杂志

AIM: To investigate the changes of expression of calcium-sensing receptor(CaSR) in the rat cardiac tissue at different age and its relation with anoxia-reperfusion(A/R) injury.METHODS: RT-PCR was used to detect the mRNA expression of CaSR.The A/R injury was remodeled in vitro,and the ultrastructure of cardiac tissue was observed under transmission electron microscope.RESULTS: The expression of CaSR mRNA in the rat cardiac tissue increased gradually after birth,and reached to its maximum in the 1st month.In the 2nd to 3rd month,the expression were almost equal to that at birth and then increased again to a higher level.The expression level of CaSR mRNA increased more significantly than those in control groups after 40 min of anoxia and reperfusion of 1 h and 2 h, and decreased after 3 h and 4 h.Moreover,the longer the reperfusion time lasted,the more serious the changes of ultrastructure were observed.CONCLUSION: Our results demonstrate that the CaSR is expressed in the rat cardiac tissue.The mRNA expression of CaSR changes with age and is involved in the anoxia-reperfusion injury.

EXPRESSION AND ELECTROPHYSIOLOGICAL CHARACTERISTICS OF L-TYPE CALCIUM CHANNEL IN RAT BONE MESENCHYMAL STEM CELLS / 解剖学报

Objective To explore the electrophysiological characteristics and the expression of mRNA and protein of L-type calcium channel in rat bone mesenchymal stem cells(MSCs). Methods MSCs were isolated,cultured and purified.RT-PCR was used to detect the mRNA expression of ?1C,?1D,?1H,?1S.The protein expression of L-type calcium channel(?1C) was testified by immunohistochamical.Ion currents were recorded in MSCs using whole-cell patch clamp technques.Results CD29,CD44,CD106 expressed in about 93% MSCs and CD14,CD34,CD45 expressed negatively.A high expression of mRNA in ?1C was detected by RT-PCR but no expressions were observed in ?1D,?1G,?1H,?1S.Immunofluorescent double labeling showed an expression of ?1C subunits in MSCs.Moreover,inward currents were recorded in 16 of 36 cells using whole-cell patch clamp techniques.The currents were activated around-30?mV and peaked at 0 to 10?mV and were blocked by nifedipine(10??mol/L).These cells had larger currents with Ba~(2+)(10?mmol/L) in bath solution than with Ca~(2+)(2?mmol/L).Conclusion The results indicated that adult rat MSCs expresse functional L-type calcium channels.It is possible that this channel plays a role on the proliferation and differentiation of MSCs.