Spinal anesthesia by local anesthetics stimulates the enzyme protein kinase C and induces the expression of an immediate early oncogene, c-Fos.
To understand the biochemical mechanisms involved in spinal anesthesia, we measured protein kinase C (PKC) activity and expression of immediate early oncogene protein, c-Fos, in the spinal cord. Spinal anesthesia was induced in mice using intrathecal injection of either 10 microL procaine or tetracaine (0.067 M/approximately 2%). Control groups were treated with either saline or ethanol. Animals were killed at 1, 5, and 15 min after the injection and the caudal 3 cm of the spinal cord was processed for biochemical analysis. PKC activity was measured by the transfer of a phosphate group from [gamma-32P]adenosine 5'-triphosphate to the threonine group on a synthetic peptide specific for PKC. Western blot analysis was used to detect changes in c-Fos protein expression. When compared to saline-treated controls, PKC activity was increased significantly (P < 0.0005) in procaine- and tetracaine-treated groups whereas ethanol decreased PKC activity. The less lipid-soluble procaine produced a larger increase in PKC activity than did the more lipid-soluble tetracaine. Moreover, parallel to the effect on PKC activity, procaine was more potent than tetracaine as a c-Fos inducer. These results implicate some role for a PKC- and c-Fos-dependent pathway in the mechanism of spinal anesthesia. However, these results also demonstrate a lack of correlation between an increase in PKC levels and either potency or lipid solubility of the anesthetics. The increased PKC activity may not be the sole mechanism for spinal anesthesia. These data on the effects of local anesthetics on PKC activity and c-Fos in vivo are of relevance for studies aimed at delineating the biochemical basis of spinal and epidural anesthesia.
Nivarthi
R N
RN
Department of Anesthesiology, School of Medicine, New York University Medical Center, NY 10016, USA.
Grant
G J
GJ
Turndorf
H
H
Bansinath
M
M
D000775:Anesthesia, Spinal; D000779:Anesthetics, Local / Q000494:pharmacology*; D000818:Animals; D015153:Blotting, Western; D003720:Densitometry; D000431:Ethanol / Q000494:pharmacology; D008297:Male; D051379:Mice; D011343:Procaine / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D013116:Spinal Cord / Q000378:metabolism; D013748:Tetracaine / Q000494:pharmacology
D000779:Anesthetics, Local; D016760:Proto-Oncogene Proteins c-fos; D013748:Tetracaine; D000431:Ethanol; D011343:Procaine; D011493:Protein Kinase C