Nucleotide Depletion Due to Reactive Oxygen Metabolites in Endothelial Cells: Effects of Antioxidants and 3-Aminobenzamide

Abstract

ABSTRACT. Reactive osygen metabolites have an important role in ischemia-reperfusion injury. One of the sources of reactive osygen metabolites is santhine osidase, which is present in several tissues but is also released into the circulation after ischemia. We studied the effect of several potentially protective compounds on adenine nucleotide depletion induced by extracellular santhine osidase and hypoxanthine, in concentrations relevant to human pathophysiology. In umbilical vein endothelial cells prelabeled with '"C-adenine, cellular adenine nucleotides retained 64 f 9% of the initial radioactivity over a 4-11 incubation with culture medium (controls), whereas in the presence of xanthine osidase (80 mU/mL) and hyposanthine (100 phl), only 3 2 4% of radioactivity remained in cellular nucleotides, the rest appearing in catabolic products in the medium. Glutathione and 3-aminobenzamide, an inhibitor of poly-ADP-ribose polymerase, partly prevented the nucleotide depletion (adenine nucleotide radioactivity 15 f 6% to 3 3 f 13% of total), but scavengers of the Ilydrosyl radical, dimethylthiourea and DhISO, a s rvell a s vitamins E and C, were without effect. Superoside dismutase prevented the leakage of nucleotides into the culture medium but not intracellular nucleotide catabolism, whereas the latter process was decreased by catalase, consistent with predominant effects of superoside and hydrogen peroxide at the cell membrane and interior, respectively. (Pediatr Res 34: 572-576, 1993)

The Regulation of AMP-Activated Protein Kinase by H2O2

“…AMPK cascades have been postulated to respond mainly to the intracellular level of AMP or AMP:ATP ratio (1-3), and a part of our result supports this speculation. Consistent with many reports showing that H 2 O 2 evokes the intracellular ATP depletion (37)(38)(39)(40), extracellular administration of non-lethal concentration of H 2 O 2 (300 M) caused a rapid depletion of ATP and accumulation of AMP in NIH-3T3 cells (Fig. 2C).…”

Protection against Hydrogen Peroxide Induced Injury in Renal Proximal Tubule Cell Lines by Inhibition of Poly(ADP–Ribose) Synthase

“…PARS activation has been demonstrated to play an important role in survival of cultured cells in various cell types such as fibroblasts, endothelial cells and smooth muscle cells exposed to oxidants [3, 4, 5, 9]. Ischemia/reperfusion in vivo and exposure to toxicants are thought to contribute to renal dysfunction through their ability to produce injury in renal tubular epithelial cells [11, 12, 13].…”

“…Radicals, including superoxide anions, hydrogen peroxide or hydroxyl radicals [3, 4, 5], and nitric oxide or peroxynitrite [6, 7, 8]cause the breakage of DNA strands and activation of PARS. Inhibitors of PARS activity attenuate the fall in NAD and ATP and improve survival of cultured cells (e.g., fibroblasts, endothelial cells, and smooth muscle cells) exposed to oxygen–derived free radicals [3, 4, 5, 9], nitric oxide [6, 7, 8]or peroxynitrite [8]. However, the inhibition of PARS does not provide general protection in all tissue, because PARS inhibitors did not protect oxidant–induced cell death in hepatocytes [10].…”

Inhibition of the activity of poly(ADP ribose) synthetase reduces ischemia–reperfusion injury in the heart and skeletal muscle

“…Radicals including superoxide anions, hydrogen peroxide or hydroxyl radicals (3)(4)(5), and NO or peroxynitrite (6)(7)(8) cause the breakage of DNA strands and activation of PARS. Inhibitors of PARS activity attenuate the fall in NAD and ATP and improve survival of cultured cells (e.g., fibroblasts, endothelial cells, and smooth muscle cells) exposed to oxygen-derived free radicals (3)(4)(5)9), NO (6)(7)(8), or peroxynitrite (8). The formation of radicals contributes to the ''reperfusion injury'' of previously ischemic organs, including the heart (10) and the skeletal muscle (11).…”