Figure 8

Hypothetical changes in the energy metabolism of cold-adapted endothelial cells. The rate-limiting enzyme, phosphofructokinase (PFK), was down-regulated at 25°C and potentially redirects the carbohydrate flux into the pentose phosphate pathway for increased reduction of NADP⁺ to NADPH. Aldolase (ALDOA, ALDOC), glyceraldehyde phosphate dehydrogenase (GAPDH), phosphoglycerate kinase (PGK1), enolase (ENO1, ENO2, ENO3), pyruvate kinase (PKM2). were up-regulated at 25°C, implicating a possible inflow of intermediate metabolites, like glycerol, into the glycolytic pathway. The increase in lactate dehydrogenase (LDHA, LDHAL6A, LDHAL6B) suggests that cold-adapted endothelium may have a greater reliance on aerobic glycolysis and a lesser reliance on mitochondrial respiration for their energy requirements. 6-PGL, 6-phosphoglucono-δ-lactone; 6-PG, 6-phosphogluconate; G-3-P, glycerol-3-phosphate; DHAP, dihydroxyacetone phosphate; 1,3-DPG, 1,3-diphosphoglycerate; 3-PG, 3-phosphoglycerate; 2-PG, 2-phosphoglycerate; PEP, phosphoenolpyruvate.