Brain energetics and tolerance to anoxia in deep hypothermia.
The remarkable time-resolution enhancement by deep lethargic hypothermia (15 degrees C rectal temperature, "cold narcosis," "anesthesia by internal cold") of metabolic events in the rat brain after oxygen deprivation has been exploited to monitor metabolic changes by in vivo (31)P-NMR. A correlation was established between the bioenergetic status of the brain and physiological descriptors of tolerance (survival and revival times) determined in parallel experiments with large series of animals. Spectral peak integrals were transformed into absolute concentrations by comparison to biochemically determined time series of data obtained in freeze-trapping experiments conducted under identical conditions. Serial spectra were used to reconstruct the time-course kinetics of intracellular brain pH and of concentration changes of inorganic phosphate, phosphocreatine, ATP, and ADP. Both the biochemical and NMR time series of data were simultaneously fitted by a set of exponential kinetic equations accounting for relationships imposed by the Lohmann and adenylate kinase reactions. Depletion profiles were then computed for a number of descriptors of brain energy status (energy charge, phosphorylation potential, total adenylate, and primary energy stores expressed as the sum of high-energy phosphate-bond equivalents). The results contribute to the understanding of the role of brain energetics in tolerance to oxygen deprivation.
Andjus
Radoslav K
RK
University of Belgrade, Yugoslavia.
Dzakula
Zeljko
Z
Markley
John L
JL
Macura
Slobodan
S
D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000263:Adenylate Kinase / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology*; D004734:Energy Metabolism; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007035:Hypothermia; D000860:Hypoxia / Q000150:complications* / Q000473:pathology*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010710:Phosphates / Q000378:metabolism; D010725:Phosphocreatine / Q000378:metabolism; D010759:Phosphorus Isotopes; D051381:Rats
D010710:Phosphates; D010759:Phosphorus Isotopes; D010725:Phosphocreatine; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000263:Adenylate Kinase; D005947:Glucose