Hydroperoxide-induced oxidative stress impairs heart muscle cell carbohydrate metabolism

Abstract

Hydrogen peroxide (H2O2) may incite cardiac ischemia-reperfusion injury. We evaluate herein the influence of H2O2-induced oxidative stress on heart muscle hexose metabolism in cultured neonatal rat cardiomyocytes, which have a substrate preference for carbohydrate. Cardiomyocyte exposure to 50 microM-1.0 mM bolus H2O2 transiently activated the pentose phosphate cycle and thereafter inhibited cellular glucose oxidation and glycolysis. These metabolic derangements were nonperoxidative in nature (as assessed in alpha-tocopherol-loaded cells) and occurred without acute change in cardiomyocyte hexose transport or glucose/glycogen reserves. Glycolytic inhibition was supported by the rapid, specific inactivation of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). The degree of GAPDH inhibition correlated directly with the magnitude of the oxidative insult and was independent of both metal-catalyzed H2O2 reduction to free radicals and lipid peroxidation. Severe GAPDH inhibition was required for a rate-limiting effect on glycolytic flux. Cardiomyocyte pyruvate dehydrogenase was also inhibited by H2O2 overload, but to a lesser degree than GAPDH such that entry of hexose-derived acetyl units into the tricarboxylic acid cycle was not as restrictive as GAPDH inactivation to glycolytic ATP production. An increase in phosphofructokinase activity accompanied GAPDH inactivation, leading to the production and accumulation of glycolytic sugar phosphates at the expense of ATP equivalents. Cardiomyocyte treatment with iodoacetate or 2-deoxyglucose indicated that GAPDH inactivation/glycolytic blockade could account for approximately 50% of the maximal ATP loss following H2O2 overload. Partial restoration of GAPDH activity after a brief H2O2 "pulse" afforded some ATP recovery. These data establish that specific aspects of heart muscle hexose catabolism are H2O2-sensitive injury targets. The biochemical pathology of H2O2 overload on cardiomyocyte carbohydrate metabolism has implications for post-ischemic cardiac bioenergetics and function.

Role of glycolysis inhibition and poly(ADP‐ribose) polymerase activation in necrotic‐like cell death caused by ascorbate/menadione‐induced oxidative stress in K562 human chronic myelogenous leukemic cells

“…Supporting this hypothesis, it has been reported that H 2 O 2 stopped the glycolytic flow and inactivated GAPDH. 25,26 These effects may be the consequence of the depletion of intracellular NAD 1 via PARP activation and/or the inactivation of GAPDH by S-nitrosylation and formation of sulfenic acid. 27 Our results show that inhibition of GAPDH is not enough to explain the dramatic drop in ATP content and the inhibition in the formation of lactate caused by ascorbate/menadione.…”

Regulatory crosstalk of the metabolic network

“…This change yields two molecules of NADPH Review Trends in Biochemical Sciences Vol. 35 No.4 for every glucose equivalent, but is energetically costly [66,67]. The redirection is mediated by two different mechanisms that, interestingly, follow each other over time.…”

Maternal Diabetes In Vivo and High Glucose In Vitro Diminish GAPDH Activity in Rat Embryos

“…A possible consequence of excess ROS generation in the mitochondria would be increased ROS leakage and inhibition of the cytosolic glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH). This enzyme has displayed sensitivity to ROS in several different conditions of oxidative stress (16). This sensitivity resides in the thiol group of cysteine residue 149 in the active site of the enzyme (17,18).…”

“…Inhibition of GAPDH has pronounced metabolic consequences, such as accumulation of glycolytic substrates before the GAPDH enzyme (16,21) and enhanced activity in the polyol and hexosamine pathways (22). In addition, alterations in phosphoinositide metabolism and enhanced formation of glycosylation products are possible effects of inhibited glycolysis at the GAPDH step (15).…”