Temperature, hematocrit, pH, and glucose 4-way ANOVA of cytochrome C oxidase redox status during systemic cold circulatory arrest in swine.
Various investigators using near infrared spectroscopy (NIRS) have reported differing patterns of cytochrome C oxidase (cytochrome a,a3) redox status in similar brain oxygenation studies. We investigated whether distinctive differences could be due to combinations of variations in temperature, hematocrit, pH, and glucose.


METHODS
Thirty-six healthy 10 kg commercial juvenile swine on cardiopulmonary bypass underwent 2-8 sequential periods of circulatory arrest. Prior to each arrest, key physiological variables were adjusted to match a random selection of one of 81 combinations of high, normal, or low levels of hypothermia, hematocrit, pH, and serum glucose. In the course of the study, the combinations were repeated twice to yield 162 NIRS data sets.


RESULTS
The mean rate of change in net oxidized minus reduced cytochrome a,a3 redox status in the brain following 7.5 min of ischemia was 0.49 +/- 0.26 micromol L(-1) min(-1), and, the corresponding mean magnitude of change was -1.23 +/- 0.57 micromol L(-1). The rate of change was influenced by temperature but not by hematocrit, pH, or glucose, either singly or in combination.


CONCLUSIONS
The respiratory response in mitochondria during systemic circulatory arrest is significantly influenced by temperature.
Gagnon
Roy E
RE
Department of Pediatrics, Children's & Women's Health Centre, University of British Columbia, Vancouver, Canada.
Gagnon
Faith A
FA
Macnab
Andrew J
AJ
LeBlanc
Jacques G
JG
D000818:Animals; D001786:Blood Glucose / Q000502:physiology*; D002315:Cardiopulmonary Bypass; D019069:Cell Respiration / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003576:Electron Transport Complex IV / Q000378:metabolism*; D004734:Energy Metabolism / Q000502:physiology*; D006324:Heart Arrest, Induced; D006400:Hematocrit; D006863:Hydrogen-Ion Concentration; D007036:Hypothermia, Induced; D020925:Hypoxia-Ischemia, Brain / Q000378:metabolism* / Q000503:physiopathology; D008928:Mitochondria / Q000378:metabolism; D010084:Oxidation-Reduction; D019265:Spectroscopy, Near-Infrared; D034421:Sus scrofa; D013696:Temperature
D001786:Blood Glucose; D003576:Electron Transport Complex IV