title: [Electrophysiological characteristic of ATP-activated currents of trigeminal ganglion neurons with different diameter in rat].
abstract: OBJECTIVE
  To explore the characteristic of ATP-activated current in trigeminal ganglion (TG) neurons of rat.
  
  
  METHODS
  Whole-cell patch-clamp was performed.
  
  
  RESULTS
  (1) The majority (92.1%) of TG neurons responded to ATP applied externally with inward currents. We recorded three distinct ATP-activated currents: fast, slow and intermediate, which were concentration-dependent. (2) In general, the fast ATP-activated currents were distributed mainly in small-diameter TG neurons, the slow ATP-activated currents were distributed mainly in large-diameter TG neurons, and the intermediate ATP-activated currents were distributed mainly in intermediate-diameter TG neurons. (3) The time course of rising phase from 10% to 90% of the three distinct ATP-activated currents were as follows: fast: (33.6 +/- 4.5) ms; intermediate: (62.2 +/- 9.9) ms; slow: (302.1 +/- 62.0) ms, and that of desensitizing phase were (399.4 +/- 58.2) ms (fast), and > 500 ms (slow) respectively. (4) From the current-voltage relationship curves, it can be seen that the reversal potential values of the three distinct ATP-activated currents were the same, all being 0-5mV. And they all were characterized by inward rectification. (5) The dose-response curve for fast ATP-activated current shifted downwards as compared with the intermediate ATP-activated current, and that for the slow ATP-activated current shifted upwards.
  
  
  CONCLUSIONS
  The EC50s of the three curves tended to be identical. The results suggested that three kinds of distinct ATP-activated currents could be mediated by various subtypes of P2X receptors assembled by different subunits, and the subtypes existed in TG neurons of different diameters and transmit different information.
authors.affiliation: Department of Physiology, Medical College, Wuhan University of Science and Technology, Wuhan 430080, USA.
authors.forename: Yu-Qin
authors.initials: YQ
authors.lastname: Zhang
authors.forename: Jia-Lie
authors.initials: JL
authors.lastname: Luo
authors.forename: Hui
authors.initials: H
authors.lastname: Nie
authors.forename: Fan
authors.initials: F
authors.lastname: Zhu
authors.forename: Zhi-Wang
authors.initials: ZW
authors.lastname: Li
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D008564:Membrane Potentials; D009474:Neurons / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000378:metabolism*; D012668:Trigeminal Ganglion / Q000502:physiology*
chemical_list: D018048:Receptors, Purinergic P2