OFF response of bullfrog cones is shaped by terminal ionotropic GABA receptors.
We recently reported an ionotropic GABA receptor expressed at the bullfrog retinal cone terminal that is potentiated by the GABA(A) receptor antagonist bicuculline (BIC) and suppressed by the GABA(C) receptor antagonist imidazole-4-acetic acid (I4AA) . In this study, by using the patch clamp technique in current clamp mode, we show that activation of this GABA receptor causes voltage changes of cones, which are closely dependent on the membrane potential level in relation to the chloride equilibrium potential of the cells. Furthermore, the OFF overshoot of cone light responses is enhanced or diminished when this receptor is potentiated by BIC or suppressed by I4AA, suggesting the involvement of this GABA receptor in shaping OFF light responses of bullfrog cones.
Liu
Jian
J
Institute of Neurobiology, Institutes of Brain Science, Fudan University, 138 Yixueyuan Road, Shanghai 200031, PR China.
Yang
Xiong-Li
XL
D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D008027:Light; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D010775:Photic Stimulation; D017729:Presynaptic Terminals / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D011892:Rana catesbeiana; D011963:Receptors, GABA-A / Q000187:drug effects / Q000378:metabolism*; D012160:Retina / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D017949:Retinal Cone Photoreceptor Cells / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects; D014785:Vision, Ocular / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D005680:gamma-Aminobutyric Acid / Q000378:metabolism* / Q000494:pharmacology
D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid