Exogenous ethyl pyruvate versus pyruvate during metabolic recovery after oxidative stress in neonatal rat cerebrocortical slices.
BACKGROUND
Exogenous pyruvate and ethyl pyruvate (EP), the key ingredient in a new Ringer's solution in clinical trials, are antioxidants as well as metabolic substrates. In vivo studies show both to be protective in oxidative stress, with EP being better. The authors used an acute rat brain slice preparation to compare EP and pyruvate rescue after H(2)O(2) oxidative stress, asking whether EP was again better and whether its actions were exclusively metabolic.


METHODS
Oxygenated neonatal P7 cerebrocortical slices were exposed for 1 h to 2 mM H(2)O(2), and recovered for 4 h with artificial cerebrospinal fluid having 2 mM glucose and (1) 20 mM EP, (2) 20 mM pyruvate, or (3) 1 mM of the nonmetabolizable radical scavenger N-tert-butyl-alpha-phenylnitrone (PBN). Perchloric acid extracts were studied with 31P/1H nuclear magnetic resonance at 14.1 T. Acute cell injury was assessed by counting terminal deoxynucleotidyl transferase-mediated uridine 5'-triphosphate-biotin nick end labeling (TUNEL)-stained cells.


RESULTS
At the end of recovery, preservation of adenosine triphosphate and N-acetylaspartate was better with EP than with pyruvate. Adenosine triphosphate preservation was best when PBN and EP were coadministered. 1H nuclear magnetic resonance revealed changes in lactate, alanine, gamma-aminobutyric acid, glutamate, glutamine, succinate, taurine, and myoinositol. Two-dimensional [1H-13C] heteronuclear single quantum coherence spectroscopy found that 13C-EP administration produced the same tricarboxylic acid metabolites as C-pyruvate. TUNEL-positive cell percentages with EP were less than half of those for PBN or pyruvate rescue (P < 0.05).


CONCLUSIONS
EP enters cells, provides pyruvate as a tricarboxylic acid substrate, and is more protective. Although EP provides metabolic protection of adenosine triphosphate levels, it does not maximize antioxidant protection.
Zeng
Jianying
J
Department of Anesthesia and Perioperative Care, The University of California, San Francisco, CA, USA.
Liu
Jia
J
Yang
Guo-Yuan
GY
Kelly
Mark J S
MJ
James
Thomas L
TL
Litt
Lawrence
L
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D000975:Antioxidants / Q000494:pharmacology; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D002452:Cell Count; D002540:Cerebral Cortex / Q000187:drug effects* / Q000378:metabolism*; D002952:Citric Acid Cycle / Q000187:drug effects; D003497:Cyclic N-Oxides / Q000494:pharmacology; D053938:DNA Fragmentation / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D020287:In Situ Nick-End Labeling; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D018696:Neuroprotective Agents; D018384:Oxidative Stress / Q000187:drug effects*; D010472:Perchlorates / Q000378:metabolism; D011773:Pyruvates / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D000975:Antioxidants; D003497:Cyclic N-Oxides; D016166:Free Radical Scavengers; D018696:Neuroprotective Agents; D010472:Perchlorates; D011773:Pyruvates; C046522:ethyl pyruvate; D001224:Aspartic Acid; C029217:phenyl-N-tert-butylnitrone; D000255:Adenosine Triphosphate; C000179:N-acetylaspartate