• Miljen M Jagodic, Sriyani Pathirathna, Pavle M Joksovic, WooYong Lee, Michael T Nelson, Ajit K Naik, Peihan Su, Vesna Jevtovic-Todorovic, and Slobodan M Todorovic.
• Department of Anesthesiology, University of Virginia Health System, Mail Box 800710, Charlottesville, VA 22908-0710, USA.
• J. Neurophysiol. 2008 Jun 1; 99 (6): 3151-6.

AbstractRecent data indicate that peripheral T-type Ca2+ channels are instrumental in supporting acute pain transmission. However, the function of these channels in chronic pain processing is less clear. To address this issue, we studied the expression of T-type Ca2+ currents in small nociceptive dorsal root ganglion (DRG) cells from L4-5 spinal ganglia of adult rats with neuropathic pain due to chronic constrictive injury (CCI) of the sciatic nerve. In control rats, whole cell recordings revealed that T-type currents, measured in 10 mM Ba2+ as a charge carrier, were present in moderate density (20 +/- 2 pA/pF). In rats with CCI, T-type current density (30 +/- 3 pA/pF) was significantly increased, but voltage- and time-dependent activation and inactivation kinetics were not significantly different from those in controls. CCI-induced neuropathy did not significantly change the pharmacological sensitivity of T-type current in these cells to nickel. Collectively, our results indicate that CCI-induced neuropathy significantly increases T-type current expression in small DRG neurons. Our finding that T-type currents are upregulated in a CCI model of peripheral neuropathy and earlier pharmacological and molecular studies suggest that T-type channels may be potentially useful therapeutic targets for the treatment of neuropathic pain associated with partial mechanical injury to the sciatic nerve.

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