Inhibitory effect of hepatocyte growth factor on cardiomyocytes apoptosis is partly related to reduced calcium sensing receptor expression during a model of simulated ischemia/reperfusion.

Calcium-sensing receptors (CaSR) are G-protein coupled receptors which maintain systemic calcium haemeostasis, participate in hormone secretion, activation of iron channel, cell apoptosis, proliferation and differentiation. Previous studies have show CaSR induce apoptosis in isolated rat adult heart and in normal rat neonatal cardiomyocytes by G-protein-PLC-IP3 signaling transinduction. A few of studies had demonstrated that CaSR induce apoptosis in cultured neonatal rat cardiomyocytes during ischemia/reperfusion. Hepatocyte growth factor (HGF), as a mesenchymally derived heterodimeric glycoprotein, play vital role in mitogenesis, angiogenesis, cellular motility and growth and anti-apoptosis after postinfarction heart failure via activation of transmembrane tyrosine kinase cell surface receptor c-Met. However, little knowledge exists about whether anti-apoptotic role of HGF in preventing cardiomyocytes injury induced by ischemia/reperfusion is associated with downregulation of CaSR expression. We incubated primary neonatal rat ventricular cardiomyocytes in ischemia-mimetic solution for 2 h, then reincubated them in normal culture medium for 24 h to establish a model of simulated ischemia/reperfusion (I/R). Cardiomyocyte apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. The expression of CaSR mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR). In addition, we analyzed the expression of Caspase-3, Bcl-2 and Phosphoinositide 3-kinase (PI3K) by Western blotting. The simulated I/R enhances the expression of CaSR and cardiomyocyte apoptosis. GdCl3, a specific activator of CaSR, further increase the expression of CaSR and Cardiomyocyte apoptosis, along with upregulation of Caspase-3, downregulation of Bcl-2 and inhibiting PI3K phosphorylation. Combination of GdCl3 with LY294002 (a selective PI3K inhibitor) increased Cardiomyocytes apoptosis but did not increased CaSR expression. Treatment of HGF decreased I/R- and GdCl3-induced apoptosis by suppressing Caspase-3 and promoting Bcl-2 and PI3K phosphorylation expression in accordance with downregulation of CaSR expression. HGF exerts protective role in I/R-induced apoptosis at least in part by inhibiting CaSR expression along with promoting Bcl-2, suppressing Caspase-3 expression and stimulating PI3K phosphorylation signaling pathway.

[Activation of calcium-sensing receptors is associated with apoptosis in cardiomyocytes under simulated ischemia/reperfusion].

OBJECTIVE: To examine the association of activation of calcium-sensing receptors (CaSR) with apoptosis in cardiomyocytes under simulated ischemia/reperfusion. METHODS: Ventricular cardiomyocytes of neonatal rats were incubated in ischemia-mimetic solution for 2 h, then re-incubated in normal culture medium for 24 h to establish a model of simulated ischemia/reperfusion (I/R). Cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL assay). The expression of CaSR mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of Caspase -3 and Bcl-2 was detected by Western blotting. RESULT: The simulated I/R enhanced the expression of CaSR and cardiomyocyte apoptosis. GdCl(3), a specific activator of CaSR, further increased the expression of CaSR and cardiomyocyte apoptosis, along with upregulation of Caspase-3 and downregulation of Bcl-2. CONCLUSION: CaSR is associated with I/R injury and apoptosis in neonatal rat ventricular cardiomyocytes via suppressing Bcl-2 and promoting Caspase -3 expression.

[Hepatocyte growth factor attenuates ischemia/reperfusion induced cardiomyocyte apoptosis via downregulating calcium sensing receptor expression].

OBJECTIVE: To examine whether the anti-apoptotic effect of hepatocyte growth factor (HGF) in cardiomyocytes underwent ischemia/reperfusion (I/R) is associated with downregulation of calcium sensing receptor (CaSR) mRNA expression. METHODS: Neonatal rat cardiomyocytes were isolated and randomly divided into 7 groups: control, I/R, GdCl(3), GdCl(3) + NiCl(2) + CdCl(2), GdCl(3) + LY294002, GdCl(3) + HGF, GdCl(3) + HGF + LY294002.I/R was established by incubating primary neonatal rat ventricular cardiomyocytes in ischemia-mimetic solution for 2 h, then reincubated in normal culture medium for 24 h. Cardiomyocyte apoptosis was detected by TUNEL. The expression of CaSR mRNA was detected by reverse transcriptase polymerase chain reaction (RT-PCR). The expression of Caspase-3, Bcl-2 and Phosphoinositide-3 Kinase (PI3K) was analyzed by Western blot. RESULTS: I/R enhanced the expression of CaSR mRNA (I/R: 2.62 ± 0.41, control: 1.00 ± 0.31, P < 0.01) and cardiomyocyte apoptosis [I/R: (15.32 ± 2.54)%, control: (2.90 ± 1.45)%, P < 0.01]. GdCl(3) further increased the expression of CaSR mRNA (GdCl(3): 4.46 ± 0.62, I/R: 2.62 ± 0.41, P < 0.01) and cardiomyocyte apoptosis [GdCl(3): (25.36 ± 2.60)%, I/R: (15.32 ± 2.54)%, P < 0.01], along with upregulation of Caspase-3 (GdCl(3): 1.93 ± 0.28, I/R: 1.50 ± 0.21, P < 0.01), downregulation of Bcl-2 (GdCl(3): 0.82 ± 0.18, I/R: 1.71 ± 0.30, P < 0.01) and PI3K phosphorylation inhibition (I/R: 0.87 ± 0.08, GdCl(3): 0.61 ± 0.07, P < 0.01). Combination of GdCl(3) with LY294002 further enhanced cardiomyocytes apoptosis [GdCl(3) + LY294002: (32.6 ± 3.42)%, GdCl(3): (25.36 ± 2.60)%, P < 0.01] but did not affect CaSR mRNA expression (GdCl(3) + LY294002: 4.27 ± 0.56, GdCl(3): 4.46 ± 0.62, P > 0.05). HGF decreased I/R- and GdCl(3)-induced apoptosis [GdCl(3) + HGF: (11.8 ± 1.89)%, GdCl(3): (25.36 ± 2.60)%, P < 0.05] by suppressing Caspase-3 (GdCl(3) + HGF: 1.12 ± 0.23, (GdCl(3): 1.93 ± 0.28, P < 0.05; GdCl(3) + HGF + LY294002: 1.87 ± 0.31, GdCl(3) + LY294002: 3.86 ± 0.47, P < 0.05) and promoting Bcl-2 (GdCl(3) + HGF: 2.56 ± 0.54, GdCl(3): 0.82 ± 0.18, P < 0.05; GdCl(3) + HGF + LY294002: 1.68 ± 0.28, GdCl(3) + LY294002: 0.68 ± 0.13, P < 0.05) and PI3K phosphorylation expression (GdCl(3) + HGF: 2.87 ± 0.21, GdCl(3): 0.61 ± 0.07, P < 0.05; GdCl(3) + HGF + LY294002: 2.01 ± 0.14, GdCl(3) + LY294002: 0.44 ± 0.10, P < 0.05) in accordance with downregulation of CaSR mRNA expression (GdCl(3) + HGF: 1.46 ± 0.37, GdCl(3): 4.46 ± 0.62, P < 0.01). CONCLUSION: HGF exerts protective role in I/R-induced apoptosis at least in part by inhibiting CaSR mRNA expression along with promoting Bcl-2, suppressing Caspase-3 expression and stimulating PI3K phosphorylation signaling pathway.

A correlation between acute kidney injury and myonecrosis after scheduled percutaneous coronary intervention.

Slight elevations in cardiac troponin I and T are frequently observed after percutaneous coronary intervention (PCI). Contrast-induced acute kidney injury (CI-AKI) is a complex syndrome induced by exposure to intravascular contrast media (CM). Currently, the relationships between the CM, pre-existing kidney insufficiency, CI-AKI, and myonecrosis after elective PCI are unclear. To investigate the relationship between CI-AKI and post-procedural myonecrosis (PMN) after PCI, we analyzed 327 non-ST-segment elevation acute coronary syndrome subjects undertaking elective PCI. The levels of cardiac troponins (cTns), cTnI and cTnT, at baseline and on at least one occasion 18-24 h after PCI were measured. We also recorded serum levels of creatinine (SCr) and the urine albumin:creatinine ratio (ACR) before coronary angiography, and 24-48 h and 48-72 h after contrast administration. A post-procedure increase in cTns was detected in 16.21% (53/327) of subjects with cTns levels >99th to 5×99th percentile upper reference limit (URL). Twenty-seven patients (8.26%) developed CI-AKI. CI-AKI occurred more often in subjects with PMN than in those without PMN (20.8% versus 5.8%, respectively, P=0.001). Multiple logistic regression analysis revealed that pre-existing microalbuminuria (MA) was an important independent predictor of PMN (OR: 3.31; 95% CI: 1.26-8.65, P=0.01). However, there was no correlation between the incidence of CI-AKI and PMN (OR: 2.38; 95% CI: 0.88-6.46, P=0.09). We conclude that pre-existing MA was not only an important independent predictor of CI-AKI but also of PMN.