Perfusate oxygen and carbon dioxide concentration influence basal microdialysate levels of striatal glucose and lactate in conscious rats.
O(2) concentration ([O(2)]) in air equilibrated solutions at room temperature is three fold higher than that in brain extracellular fluid (ECF), and CO(2) concentration ([CO(2)]) is 100 times lower. Using microdialysis the ECF is routinely dialyzed against glucose free isotonic perfusates containing 200 microM O(2) and 10 microM CO(2). In conscious rats, 2 days after probe implantation, decreasing perfusate [O(2)] from 200 to 68 microM (physiologic level) for 60 min, while maintaining a low [CO(2)] (10 microM), increased striatal dialysate glucose and lactate by 12% and 33%, respectively. The same protocol on the third day essentially had no effect on monoamine metabolites. Decreasing [O(2)] concurrent with increasing [CO(2)] to 1.3 mM (physiologic level) for 60 min increased glucose and lactate by 17% and 37%, respectively. This study demonstrates for dialysis studies of glucose and lactate, perfusates that mimic physiologic ECF [O(2)] and [CO(2)] are more appropriate.
Wang
Lei
L
Institute of Chemistry, Centre for Molecular Science, Chinese Academy of Sciences, Beijing 100080, China.
Li
Yuanzong
Y
Han
Huiwan
H
Liu
Guoquan
G
Osborne
Peter G
PG
D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology*; D003342:Corpus Striatum / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D019344:Lactic Acid / Q000378:metabolism*; D017551:Microdialysis / Q000379:methods; D010100:Oxygen / Q000494:pharmacology*; D010477:Perfusion / Q000379:methods; D051381:Rats; D012996:Solutions
D012996:Solutions; D002245:Carbon Dioxide; D019344:Lactic Acid; D005947:Glucose; D010100:Oxygen