[Effects of ropivacaine on GABA-activated currents in isolated dorsal root ganglion neurons in rats].
OBJECTIVE
To investigate the effects of ropivacaine on Gamma-aminobutyric acid(GABA)-activated currents in dorsal root ganglion (DRG) neurons in rats and discuss the analgesia mechanism of ropivacaine.


METHODS
By means of using whole-cell patch-clamp technique, to investigate the modulatory effects of ropivacaine on GABA-activated currents (I(GABA)) in acutely isolated dorsal root ganglion neurons.


RESULTS
(1) In 48 out of 73DRG cells (65.7%, 48/73), to perfusion ropivacaine bromide (0.1 - 1 000 micromol/L) were sensitive. Which produce in 0 to 380 pA current. (2) The majority of the neurons examined (74.5%, 73/98) were sensitive to GABA. Concentration of 1 - 1 000 micromol/L GABA could activate a concentration-dependent inward current, which manifested obvious desensitization, and the inward currents could be blocked byGABA-receptor selective antagonist of bicuculline (100 micromol/L). (3) After the neurons were treated with ropivacaine (0.1 - 1000 micromol/L) prior to the application of GABA (100 micromol/L) 30 s, GABA currents were obviously increased. Ropivacaine could make dose-response curve of the GABA up, EC50 is 23.46 micromol/L. Ropivacaine shifted the GABA dose-response curve upward and increased the maximum response to the contrast about 153%.


CONCLUSIONS
The enhancement of ropivacaine to DRG neurons activation of GABA current, can lead to enhancement of pre-synaptic inhibition at the spinal cord level. This may be one of the reasons for the anesthetic effect and analgesia for ropivacaine in epidural anesthesia.
The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Shihen University Medical College, Shihezi 832002, China.
Yue
Y
Yang
Jun-Qiang
JQ
Si
Chao
C
Fan
Ke-Tao
KT
Ma
Hong-Jv
HJ
Cheng
Li
L
Li
D000577:Amides / Q000494:pharmacology*; D000818:Animals; D005727:Ganglia, Spinal / Q000166:cytology / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D011963:Receptors, GABA-A / Q000502:physiology*; D000077212:Ropivacaine
D000577:Amides; D011963:Receptors, GABA-A; D000077212:Ropivacaine