Tetrodotoxin-sensitive persistent current boosts the depolarization of retinal amacrine cells in goldfish.
To light illumination retinal amacrine cells respond with graded depolarization accompanied by a spike discharge. It has been assumed that the graded depolarization is produced solely by the excitatory synaptic inputs from bipolar cells. Here we demonstrate that a tetrodotoxin (TTX)-sensitive persistent current also contributes to the graded depolarization. This current was isolated in amacrine cells of the goldfish retinal slice preparations by the whole-cell patch clamp technique. The activation threshold of the persistent current was about -50 mV, approximately 10 mV more positive than the membrane potential in the dark. Therefore, it is highly likely that the TTX-sensitive persistent current is a booster of the excitatory postsynaptic potential in amacrine cells.
Watanabe
S
S
Department of Physiology, Keio University School of Medicine, Tokyo, Japan. siwata@mc.med.keio.ac.jp
Satoh
H
H
Koizumi
A
A
Takayanagi
T
T
Kaneko
A
A
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002347:Carps; D019706:Excitatory Postsynaptic Potentials; D006054:Goldfish; D007395:Interneurons / Q000187:drug effects* / Q000528:radiation effects; D015640:Ion Channel Gating; D008027:Light; D018408:Patch-Clamp Techniques; D012964:Sodium / Q000502:physiology; D013779:Tetrodotoxin / Q000494:pharmacology*
D013779:Tetrodotoxin; D012964:Sodium