Fumonisin blunts nitric oxide-induced and nitroprusside-induced cardiomyocyte death

Abstract

The objective of this study was to determine whether nitric oxide (NO)-induced cell death in cardiomyocytes was operative through de novo synthesis of ceramide by determining whether the ceramide synthase inhibitor fumonisin blocked NO-mediated cell death. Neonatal mouse cardiomyocytes in culture were pretreated with fumonisin B1 (FB1). FB1 is a competitive inhibitor of sphinganine N-acyl transferase, also known as ceramide synthase (EC 2.3.1.24). Cell viability was assessed by the (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay, which is based on the ability of viable cells to reduce MTT. Treatment with the NO donor nitroso-glutathione (NO-GSH) for 24 h produced a significant ( p<0.05) concentration-dependent reduction in OD 570 or an increase in cell death. Sodium nitroprusside (SNP) treatment for 24 h produced a significant ( p<0.001) concentration-dependent reduction in OD 570 and an increase in cardiomyocyte cell death but the effects of SNP were greater than those of NO-GSH. FB1 significantly ( p<0.05) reduced cell death induced by either SNP or NO-GSH. The SNP (0.1 mM) increase in cell death of 36.9±2.8% was significantly ( p<0.05) reduced to 24.7±1.8% by FB1 (10 μM). The effect of FB1 was not mediated through inhibition of the cell death effects of H 2O 2, which is produced by SNP, as FB1 did not prevent H 2O 2-induced cell death. Confirmation of the ability of ceramide to produce cell death was demonstrated by the cell-permeable ceramide analogue, C 2-ceramide (100 and 200 μM), which induced, respectively, 23.4±11.3 and 78.0±3.7% increases in cell death. The cell death effects of SNP and NO-GSH are likely independent of cGMP signal transduction pathways, which are activated by either SNP or NO-GSH, as there was no significant concentration-dependent change in cardiomyocyte viability after treatment with the cell-permeable analogue dibutyryl–GMP. These data show that FB1 blunts SNP- and NO-induced cardiomyocyte death and raise the novel possibility of preventing some of SNP- or NO-induced cardiomyocyte cell death by ceramide synthase inhibition.