Electrophysiological characteristic of ATP-activated currents of trigeminal ganglion neurons with different diameter in rat / 中国应用生理学杂志

ABSTRACT

<p><b>AIM</b>To explore the characteristic of ATP-activated current in trigeminal ganglion (TG) neurons of rat.</p><p><b>METHODS</b>Whole-cell patch-clamp was performed.</p><p><b>RESULTS</b>(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.</p><p><b>CONCLUSION</b>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.</p>