Intrathecal anaesthesia alters intracellular Ca2+/Mg2+ homeostasis in the spinal cord neurones of experimental rats.
OBJECTIVE
The effect of anaesthesia induced by intrathecal injection of 6.3% MgSO4 or 4% lidocaine on intracellular electrolyte homeostasis in spinal cord neurones of a rat model was investigated.


METHODS
Intracellular Ca2+, Mg2+, Na+ and K+ concentrations were determined at different times after intrathecal administration of NaCl (saline, a control group), MgSO4 or lidocaine.


RESULTS
In both thoracic and lumbar spinal cord segments, Ca2+ concentrations rose significantly 30 min and 2 h after 6.3% MgSO4 injection, and after 24 h were still significantly increased compared with the values obtained from the control group which were subjected to sham 'anaesthesia' by saline injection (172, 121 and 108 ng mg-1 protein vs. control 23 ng mg-1 protein, respectively, in the thoracic segment and 222, 229 and 176 ng mg-1 protein vs. control 43 ng mg-1 protein, respectively, in the lumbar segment). Lidocaine injection also produced a significant increase in intracellular Ca2+ in the thoracic and lumbar spinal cord segments (69, 64 and 53 ng mg-1 protein vs. control 33.4 ng mg-1 protein and 26, 94 and 46 ng mg-1 protein vs. 23 ng mg-1 protein respectively). Only a modest rise in intracellular Mg2+ was observed after intrathecal MgSO4 or lidocaine injection (27 ng mg-1 protein vs. 23 ng mg-1 protein). Na+ and K+ concentrations decreased 24 h after MgSO4 and 1 h after lidocaine injection.


CONCLUSIONS
Intrathecal anaesthesia by MgSO4 or lidocaine alters intracellular electrolyte homeostasis in spinal cord neurones of experimental rats. A possible common mechanism of action via Ca2+ ion channels is discussed.
Bahar
M
M
Department of Anaesthesiology Assaf Harofeh Medical Centre, Zerifin 70300, affiliated to Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
Berman
S
S
Chanimov
M
M
Weissgarten
J
J
Averbukh
Z
Z
Cohen
M L
ML
Grinshpon
Y
Y
D000775:Anesthesia, Spinal; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006706:Homeostasis / Q000187:drug effects*; D007278:Injections, Spinal; D008012:Lidocaine / Q000008:administration & dosage / Q000494:pharmacology; D008274:Magnesium / Q000378:metabolism*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013054:Spectrophotometry, Atomic; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000187:drug effects
D000779:Anesthetics, Local; D008012:Lidocaine; D008274:Magnesium; D002118:Calcium