Dynamics of extracellular calcium activity following contusion of the rat spinal cord.
The role of Ca2+ in cellular injury has received particular attention in studies of acute spinal cord trauma. In this context, the spatial and temporal distribution of extracellular Ca2+ ([Ca2+]e) may have an important bearing on the development of secondary tissue injury. We therefore studied the spatial-temporal distribution of [Ca2+]e following moderate (25 g-cm) contusive injury to the rat thoracic (T9-T11) spinal cord. Double-barreled, Ca(2+)-selective microelectrodes were used to measure the magnitude and time course of [Ca2+]e at increasing depths from the dorsal spinal cord surface. After 2 h, the tissue was frozen and later analyzed for total Ca concentration using atomic absorption spectroscopy. [Ca2+]e fell at all depths, but the decrease was maximal at 250 and 500 microns from the dorsal surface, where, at 0-10 min after injury, [Ca2+]e averaged 0.09 +/- 0.03 and 0.06 +/- 0.03 mM respectively. By 2 h postinjury, [Ca2+]e recovered to nearly 1 mM across all depths. Over this time, total tissue calcium concentration ([Ca]t) was 4.54 +/- 0.16 mumol/g in injured cords vs 2.75 +/- 0.1 mumol/g in sham-operated controls. These data place emphasis on the dorsal gray matter as a principal site of ionic derangement in acute spinal cord injury. The implications of these findings are discussed with reference to secondary injury processes.
Moriya
T
T
Department of Neurosurgery, New York University Medical Center, New York.
Hassan
A Z
AZ
Young
W
W
Chesler
M
M
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure; D002118:Calcium / Q000378:metabolism*; D003288:Contusions / Q000378:metabolism* / Q000503:physiopathology; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D051381:Rats; D011919:Rats, Inbred Strains; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000503:physiopathology; D013997:Time Factors
D002118:Calcium