The signal transduction pathway of PKC/NF-κB/c-fos may be involved in the influence of high glucose on the cardiomyocytes of neonatal rats

BACKGROUND: High glucose could induce structure and function change in cardiomyocytes, PKC plays a core effect in the onset and progression of diabetic cardiomyopathy, but its underlying downstream signal transduction pathway is still not completely understood. OBJECTIVES: To study the influence of high glucose on the structure, function and signal transduction pathway of PKC (Protein Kinase C)/NF-kappaB(Nuclear factor-kappaB)/c-fos in cultured cardiomyocytes. METHODS: Using cultured cardiomyocytes of neonatal Sprague-Dawley rats as a model, groups were divided into: control group (glucose: 5 mmol/L); high glucose group (glucose: 10 mmol/L, 15 mmol/L, 20 mmol/L, 25.5 mmol/L); equimolar mannital group (5 mmol/L glucose + 20.5 mmol/L maninital); high glucose(25.5 mmol/L) add PKC inhibitor (Ro-31-8220, 50 nmol/L); high glucose (25.5 mmol/L) add NF-kappaB inhibitor (BAY11-7082, 5 mumol/L). The cellular contracting frequency and volumes were measured and the expression of PKC-alpha, PKC-beta2, p-PKC-alpha, p-PKC-beta2, NF-kappaB, p-NF-kappaB, TNF-alpha (tumor necrosis factor-alpha) and c-fos were measured by western blot or RT-PCR. RESULTS: Cardiomyocytes cultured in high glucose level, but not iso-osmotic mannital, showed an increased pulsatile frequency and higher cellular volumes consistent with the increased glucose levels, and also higher expression of PKC-alpha, PKC-beta2, p-PKC-alpha, p-PKC-beta2, NF-kappaB, p-NF-kappaB, TNF-alpha and c-fos. The addition of Ro-31-8220 and BAY11-7082 could partly reverse these changes induced by high glucose level. CONCLUSION: High glucose significantly increased the pulsatile frequency and cellular volumes of cultured cardiomyocytes via PKC/NF-kappaB/c-fos pathway, which might lead to diabetic cardiomyopathy.