title: [The effect of niflumic acid and blocker of calcium channel on the desensitization of gamma aminobutyric acid-activated current].
abstract: OBJECTIVE
  To explore the modulatory effect of niflumic acid and blocker of calcium channel on the desensitization of gamma aminobutyric acid (GABA)-activated currents in dorsal root ganglion(DRG) neurons from rat.
  
  
  METHODS
  The whole-cell patch-clamp technique was used to observe the modulatory effect of niflumic acid and blocker of calcium channel on the desensitization of GABA-activated currents in neurons freshly dissociated from rat DRG neurons.
  
  
  RESULTS
  Application of GABA (0.1-1 000 micromol/L) could induce concentration-dependent inward currents in some cells (212/223, 95.11%). GABA-(100 micromol/L) activated currents was (1.32 +/- 0.74) nA (n = 84). However, pre-application of niflumic acid (1-100 micromol/L) and nitrendipine (specific blocker of L-calcium channel)(0.1-30 micromol/L) could inhibit the GABA-activated inward current which was identified to be GABAA receptor-mediated current. The inhibitory effects of niflumic acid and nitrendipine were concentration-dependent. The suppression rate of 10 micromol/L niflumic acid and nitrendipine to GABA-activated currents were (31.60% +/- 4.87%) (n = 19) and (43.60% < or = 5.10%) (n = 5), respectively. The desensitization of GABA-activated currents had double exponential characteristic. Tau value was (14.68 +/- 5.11) s (n = 6) and (175.8 +/- 42.67) s (n = 6, r = 0.9647), respectively. Pre-application of niflumic acid (100 micromol/L) and nickel chloride (nonspecific blocker of L-calcium channel) (100 micromol/L) altered tau value of the desensitization of GABA-activated currents, tau value reduced for (4.64 +/- 2.21) s (n = 3), (43.70 +/- 14.34) s ( n = 3, r = 0.9548) and (4.64 +/- 2.21) s (n = 3), (43.70 +/- 14.34) s (n = 3, r = 0.9721).
  
  
  CONCLUSIONS
  Pre-application of niflumic acid exerts a more strong inhibitory effect on the peak value of GABA-activated current, which possibly is through blocking the calcium-activated chloride ion channel to accelerate the desensitization of GABA-activated currents.
authors.affiliation: Department of Physiology and Pathophysiology, Medical College Shihezi University, China.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Ke-Tao
authors.initials: KT
authors.lastname: Ma
authors.forename: Hong-Ju
authors.initials: HJ
authors.lastname: Cheng
authors.forename: Lei
authors.initials: L
authors.lastname: Zhao
authors.forename: Jun-Qiang
authors.initials: JQ
authors.lastname: Si
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000187:drug effects*; D005727:Ganglia, Spinal / Q000187:drug effects / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D009544:Niflumic Acid / Q000494:pharmacology*; D009568:Nitrendipine / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology
chemical_list: D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D009544:Niflumic Acid; D005680:gamma-Aminobutyric Acid; D009568:Nitrendipine