Experimental spinal cord injury induced an increase of extracellular ascorbic acid concentration in anesthetized rats: a microdialysis study.
Ascorbic acid plays important roles in mammalian central nervous system. We employed an on-line analytical system to monitor the extracellular ascorbic acid concentrations in anesthetized rat spinal cord before and after the experimental injury. A microdialysis probe (216 microm od, 200 microm id, 3 mm in length) was implanted into an anesthetized rat spinal cord (Thoratic-12). Microdialysis perfusate (2 microl/min) was collected in the sample loop (20 microl) of an on-line injector for direct injection onto a High Performance Liquid Chromatography (HPLC) system equipped with an electrochemical detector. Normal ascorbic acid concentrations in the spinal cord extracellular fluids ranged from 1.8 microM to 10.8 microM (mean +/- S.D. 5.6 +/- 2.4 microM, n = 8). The experimental spinal cord injury, induced by a lesion at T-10, gradually yet significantly increased the extracellular ascorbic acid levels. The effect of exogenous glutamate perfusion (0.2 mM, 2 mM, and 20 mM) through the microdialysis probe also increased the extracellular ascorbic acid concentrations in a dose dependent manner. These results suggested that the injury-induced ascorbic acid accumulation may result from elevated extracellular glutamate levels that are commonly observed in spinal cord injury. This on-line, continuous and automatic monitoring system can be applied to future investigations on the roles of ascorbic acid in spinal cord injuries.
Tsai
Pi-Ju
PJ
Department of Education and Research, Taichung Veterans General Hospital, Taiwan.
Chen
Wen-Ying
WY
Tzeng
Shun-Fen
SF
Liang
Wei-Ming
WM
Yang
Chung-Shi
CS
D000758:Anesthesia; D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism*; D018698:Glutamic Acid / Q000494:pharmacology; D008297:Male; D017551:Microdialysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000473:pathology
D018698:Glutamic Acid; D001205:Ascorbic Acid