A sampling artifact in the microdialysis study of changes in extracellular [Mg2+] upon spinal cord injury.
Whether depletion of a substance from the extracellular fluid by removal through the dialysis probe can affect the measured efflux of that substance into the extracellular fluid upon injury is examined. When Mg(2+)-free artificial cerebrospinal fluid was used to perfuse the microdialysis fiber, a significant increase in collected Mg2+ was observed immediately following injury. However, when [Mg2+] inside the fiber was equal to the basal concentration in the extracellular fluid, no increase in [Mg2+] was detected. The difference between the two sets of results is attributed to efflux down an increased intracellular/extracellular [Mg2+] gradient that occurs when the basal extracellular concentration is not balanced within the fiber, but not otherwise. This is a previously unreported problem with microdialysis.
Yang
J
J
Marine Biomedical Institute, University of Texas Medical Branch, Galveston 77555-1069, USA.
Robak
G
G
Liu
D
D
McAdoo
D J
DJ
D000596:Amino Acids / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D016477:Artifacts; D002555:Cerebrospinal Fluid / Q000737:chemistry; D008274:Magnesium / Q000032:analysis* / Q000378:metabolism*; D008297:Male; D017551:Microdialysis / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013119:Spinal Cord Injuries / Q000378:metabolism*; D013997:Time Factors
D000596:Amino Acids; D008274:Magnesium