Isoflurane, but Not the Nonimmobilizers F6 and F8, Inhibits Rat Spinal Cord Motor Neuron CaV1 Calcium Currents

Recio-Pinto, Esperanza PhD; Montoya-Gacharna, Jose V. MD; Xu, Fang PhD; Blanck, Thomas J. J. MD, PhD

doi: 10.1213/ANE.0000000000001111
Anesthetic Pharmacology: Research Report

BACKGROUND: Volatile anesthetics decrease Ca2+ entry through voltage-dependent Ca2+ channels. Ca2+ influences neurotransmitter release and neuronal excitability. Because volatile anesthetics act specifically on the spinal cord to produce immobility, we examined the effect of isoflurane and the nonimmobilizers F6 (1, 2-dichlorohexafluorocyclobutane) and F8 (2, 3-dichlorooctafluorobutane) on CaV1 and CaV2 Ca2+ channels in spinal cord motor neurons and dorsal root ganglion neurons.

METHODS: Using patch clamping, we compared the effects of isoflurane with those of F6 and F8 on CaV1 and CaV2 channels in isolated, cultured adult rat spinal cord motor neurons and on CaV1 and CaV2 channels in adult rat dorsal root ganglion sensory neurons.

RESULTS: In spinal cord motor neurons, isoflurane, but not F6 or F8, inhibited currents through CaV1 channels. Isoflurane and at least one of the nonimmobilizers inhibited currents through CaV1 and CaV2 channels in dorsal root ganglion neurons and CaV2 in spinal cord motor neurons.

CONCLUSIONS: The findings that isoflurane, but not nonimmobilizers, inhibited CaV1 Ca2+ channels in spinal cord motor neurons are consistent with the notion that spinal cord motor neurons might mediate isoflurane-induced immobility. Additional studies are required to examine whether inhibition of CaV1 calcium currents in spinal cord motor neurons is sufficient or whether actions on other channels/proteins contribute to isoflurane-induced immobility.

Published ahead of print December 23, 2015

From the Department of Anesthesiology, NYU Langone Medical Center, New York, New York.

Fang Xu, PhD, is currently affiliated with Weill Cornell Medical College, New York, New York.

Accepted for publication October 8, 2015.

Published ahead of print December 23, 2015

Funding: National Institutes of Health grant number R01GM50686 to Thomas J. J. Blanck. The Anesthesia Research Fund of the New York University, Department of Anesthesiology.

The authors declare no conflicts of interest.

This report was previously presented, in part, at the American Society of Anesthesiologists, 2009.

Reprints will not be available from the authors.

Address correspondence to Thomas J. J. Blanck, MD, PhD, Department of Anesthesiology, NYU Langone Medical Center, 550 1st Ave., Tisch 554, New York, NY 10016. Address e-mail to thomas.blanck@nyumc.org.

© 2016 International Anesthesia Research Society