Characterization of three types of ATP-activated current in relation to P2X subunits in rat trigeminal ganglion neurons.
In the present study, ATP-activated currents (I(ATP)s) recorded from rat trigeminal ganglion (TG) neurons using whole-cell patch clamp technique are classified into three types (F, I and S) based on the characteristics of their activation and desensitization. The time of rising phase (R(10-90)) of types F, I and S of I(ATP) is measured to be 33.6+/-4.5, 62.2+/-9.9 and 302.1+/-62.0 ms respectively, and positively correlated to cell size. The time of decaying phases (D(10-90)) of types F and S is 399.4+/-58.2 and >1500 ms, respectively. The dose-response curves for the three types of I(ATP) show that their EC(50) values are close (3.44 x 10(-5), 4.89 x 10(-5) and 4.14 x 10(-5) M for types F, I and S respectively, P>0.05). Their reversal potentials are basically the same, varying from +4 to +10 mV. In addition, using whole-cell patch clamp technique in combination with single cell immunohistochemical staining for P2X receptor subunits, our results suggest that the type distinction of ATP-activated current was associated with cell size and P2X receptor subunits: small-sized cells with type F of I(ATP) express only P2X1 and/or P2X3 subunits, while cells with types S and I of I(ATP) express P2X2 or P2X4 in addition to P2X1 and P2X3.
Luo
Jialie
J
Department of Neurobiology, Tongji Medical College, Huazhong University of Science and Technology, 13 Hangkong Road, Wuhan 430030, PR China.
Yin
Guang-Fu
GF
Gu
Yuan-Zheng
YZ
Liu
Yang
Y
Dai
Jia-Pei
JP
Li
Chaoying
C
Li
Zhi-Wang
ZW
D000255:Adenosine Triphosphate / Q000819:agonists / Q000031:analogs & derivatives / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D007150:Immunohistochemistry; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D021122:Protein Subunits / Q000187:drug effects / Q000378:metabolism; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D018048:Receptors, Purinergic P2 / Q000737:chemistry / Q000378:metabolism*; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; D058848:Receptors, Purinergic P2X4; D012668:Trigeminal Ganglion / Q000187:drug effects / Q000378:metabolism*
C546403:P2rx2 protein, rat; C546410:P2rx3 protein, rat; C548228:P2rx4 protein, rat; D021122:Protein Subunits; D058910:Purinergic P2 Receptor Agonists; D058919:Purinergic P2 Receptor Antagonists; D018048:Receptors, Purinergic P2; D058469:Receptors, Purinergic P2X; D058476:Receptors, Purinergic P2X2; D058477:Receptors, Purinergic P2X3; D058848:Receptors, Purinergic P2X4; D000255:Adenosine Triphosphate