Interstitial lactate, lactate/pyruvate and glucose in rat muscle before, during and in the recovery from global hypoxia.
BACKGROUND
Hypoxia results in an imbalance between oxygen supply and oxygen consumption. This study utilized microdialysis to monitor changes in the energy-related metabolites lactate, pyruvate and glucose in rat muscle before, during and after 30 minutes of transient global hypoxia. Hypoxia was induced in anaesthetised rats by reducing inspired oxygen to 6% O2 in nitrogen.


RESULTS
Basal values for lactate, the lactate/pyruvate ratio and glucose were 0.72 ± 0.04 mmol/l, 10.03 ± 1.16 and 3.55 ± 0.19 mmol/l (n = 10), respectively. Significant increases in lactate and the lactate/pyruvate ratio were found in the muscle after the induction of hypoxia. Maximum values of 2.26 ± 0.37 mmol/l for lactate were reached during early reperfusion, while the lactate/pyruvate ratio reached maximum values of 35.84 ± 7.81 at the end of hypoxia. Following recovery to ventilation with air, extracellular lactate levels and the lactate/pyruvate ratio returned to control levels within 30-40 minutes. Extracellular glucose levels showed no significant difference between hypoxia and control experiments.


CONCLUSIONS
In our study, the complete post-hypoxic recovery of metabolite levels suggests that metabolic enzymes of the skeletal muscle and their related cellular components may be able to tolerate severe hypoxic periods without prolonged damage. The consumption of glucose in the muscle in relation to its delivery seems to be unaffected.
Department of Anaesthesiology, University Hospital RWTH Aachen, Pauwelsstrasse 30, D-52074, Aachen, Germany. nzoremba@ukaachen.de.
Norbert
N
Zoremba
Department of Neuroscience, Charles University, 2nd Medical Faculty, V Úvalu 84, 150 06, Prague, Czech Republic. aleshomola@sezman.cz.|Institute of Experimental Medicine, Academy of Sciences of Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic. aleshomola@sezman.cz.
Aleš
A
Homola
Department of Anaesthesiology, University Hospital RWTH Aachen, Pauwelsstrasse 30, D-52074, Aachen, Germany. rrossaint@ukaachen.de.
Rolf
R
Rossaint
Department of Neuroscience, Charles University, 2nd Medical Faculty, V Úvalu 84, 150 06, Prague, Czech Republic. sykova@biomed.cas.cz.|Institute of Experimental Medicine, Academy of Sciences of Czech Republic, Vídeňská 1083, 142 20, Prague, Czech Republic. sykova@biomed.cas.cz.
Eva
E
Syková
D000818:Animals; D004734:Energy Metabolism; D005947:Glucose / Q000378:metabolism*; D000860:Hypoxia / Q000209:etiology / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D018482:Muscle, Skeletal / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar
D019344:Lactic Acid; D019289:Pyruvic Acid; D005947:Glucose