Purpose: The aim of this study was to determine the invitro effect of glutamine and insulin on apoptosis, mitochondrial membrane potential, cell permeability and inflammatory cytokines in hyperglycemic umbilical vein endothelial cell. 

Materials and methods: In our study, human umbilical vein endothelial cells were grown and subjected to hyperglycemia and the effect of glutamine and insulin. Mitochondrial functions and the production of inflammatory cytokines were determined using florescence analysis and multiple cytotoxicity assays. Apoptosis was analyzed by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. 

Results: Our results demonstrate that glutamine maintains the integrity of the mitochondria by reducing the cell permeability and cytochrome c intensity, and increasing the mitochondrial membrane potential. Cytochrome c intensity was significantly (p < 0.005) reduced when cells were treated with glutamine. TUNEL assay revealed significantly reduced apoptosis (p < 0.005) in cells treated with glutamine. Our data further suggest that glutamine alone or in combination with insulin can modulate inflammatory cytokines. IL-10 (p < 0.05), IL-6 (p < 0.005) and VEGF were up regulated while TNFα was down regulated after treating glutamine alone or in combination with insulin. 

Conclusion: Our data conclude that glutamine alone or in combination with insulin can positively disrupt mitochondrial stress and cell permeability in umbilical vein endothelial cell under hyperglycemic conditions. At the same time our data support that glutamine regulates the expression of inflammatory cytokines and maintains the balance of the mitochondria in a cytoprotective manner, whose dysfunction in the hyperglycemic endothelial cells may reflect the degree of systemic injury in severe sepsis.