[Effects of capsaicin on IA and IK in cultured trigeminal ganglion neurons of rat].
OBJECTIVE
To investigate the effect of capsaicin on IA and IK in cultured rat trigeminal ganglion (TG) neurons.


METHODS
Whole-cell patch clamp technique was used to record the IA and IK before and after capsaicin perfusion at different concentrations.


RESULTS
In capsaicin-sensitive (CS) neurons, capsaicin was shown to selectively inhibit IA in dose-dependent manner, the IC50 was 0.99 micromol x L(-1). Yet capsaicin showed no inhibitory effect on IK, capsaicin (10 micromol x L(-1)) only slightly inhibited IK by 13.2%. In capsaicin-insensitive (CIS) neurons, capsaicin (1 micromol x L(-1)) showed no significant inhibitory effect on IA and IK, capsaicin (10 micromol x L(-1)) only slightly inhibited IA and IK by 16.8% and 15.3%, respectively. Neither 1 micromol x L(-1) nor 10 micromol x L(-1) capsaicin showed effect on the G-V curve of IA and IK.


CONCLUSIONS
Capsaicin was found to selectively inhibit the IA current in CS neurons, and this effect may contribute to hyperalgesia when capsaicin was first used.
Fu
Hui
H
Department of Pharmacology, Tongli Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Liu
Hui
H
Cao
Xue-hong
XH
Xiang
Ji-zhou
JZ
Liu
Lie-ju
LJ
D000818:Animals; D002211:Capsaicin / Q000494:pharmacology*; D002478:Cells, Cultured; D005260:Female; D008297:Male; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques; D024642:Potassium Channels, Voltage-Gated / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012668:Trigeminal Ganglion / Q000166:cytology / Q000502:physiology*
D024642:Potassium Channels, Voltage-Gated; D002211:Capsaicin