TY - JOUR
T1 - Dihydropyridine-sensitive calcium currents in bipolar cells of salamander retina are inhibited by reductions in extracellular chloride
AU - Thoreson, Wallace B.
N1 - Funding Information:
Supported by NEI grant EY-10542, Nebraska Lions Eye Institute, Gifford Foundation, and a Career Development Award from Research to Prevent Blindness. The author wish to thank E.J. Bryson for technical assistance and J. Gottesman, S. Stella and P. Witkovsky for comments on the manuscript.
PY - 2000/2/25
Y1 - 2000/2/25
N2 - Dihydropyridine-sensitive calcium currents (I(Ca)) in photoreceptors are unusual in that they can be inhibited by reductions in extracellular chloride. The present study examined whether I(Ca) in retinal bipolar cells, which as in photoreceptors mediates sustained neurotransmission, is also inhibited by reductions in chloride. Nystatin-perforated patch, whole cell recordings were obtained from bipolar cells in a retinal slice preparation of larval tiger salamander. In the presence of Ba2+, voltage steps above -40 mV evoked sustained inward currents, which were enhanced by the dihydropyridine, (-)BayK8644, and inhibited by nisoldipine. Similar to photoreceptors, replacing Cl- with gluconate or CH3SO4 inhibited bipolar cell I(Ca) and produced a negative shift in the current/voltage relationship. Thus, sensitivity to Cl- may be a more general property of L-type Ca2+ channel subtypes that mediate sustained neurotransmission. (C) 2000 Elsevier Science Ireland Ltd.
AB - Dihydropyridine-sensitive calcium currents (I(Ca)) in photoreceptors are unusual in that they can be inhibited by reductions in extracellular chloride. The present study examined whether I(Ca) in retinal bipolar cells, which as in photoreceptors mediates sustained neurotransmission, is also inhibited by reductions in chloride. Nystatin-perforated patch, whole cell recordings were obtained from bipolar cells in a retinal slice preparation of larval tiger salamander. In the presence of Ba2+, voltage steps above -40 mV evoked sustained inward currents, which were enhanced by the dihydropyridine, (-)BayK8644, and inhibited by nisoldipine. Similar to photoreceptors, replacing Cl- with gluconate or CH3SO4 inhibited bipolar cell I(Ca) and produced a negative shift in the current/voltage relationship. Thus, sensitivity to Cl- may be a more general property of L-type Ca2+ channel subtypes that mediate sustained neurotransmission. (C) 2000 Elsevier Science Ireland Ltd.
KW - Anion
KW - Electrophysiology
KW - Gluconate
KW - L-type calcium current
KW - Ribbon synapse
KW - Sustained neurotransmission
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U2 - 10.1016/S0304-3940(00)00795-3
DO - 10.1016/S0304-3940(00)00795-3
M3 - Article
C2 - 10675784
AN - SCOPUS:0033976202
SN - 0304-3940
VL - 280
SP - 155
EP - 158
JO - Neuroscience Letters
JF - Neuroscience Letters
IS - 3
ER -