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Rapid calcium-current kinetics in synaptic terminals of goldfish retinal bipolar neurons

Published online by Cambridge University Press:  01 November 1998

STEVEN MENNERICK
Affiliation:
Department of Neurobiology and Behavior, State University of New York, Stony Brook
GARY MATTHEWS
Affiliation:
Department of Neurobiology and Behavior, State University of New York, Stony Brook

Abstract

Onset and offset of calcium current in response to short, depolarizing voltage pulses were studied in giant synaptic terminals of goldfish bipolar neurons. Tail-current decays were extremely rapid (80 μs at −70 mV), and exponentially slowed at more positive repolarization potentials. The amplitude of tail current following voltage pulses varied with the pulse amplitude, according to a Bolzmann distribution with a V1/2 of −27.6 mV and a slope factor of 13.8 mV. When interpreted with a Hodgkin-Huxley model, calcium-current onset was best described by m2 kinetics and a time constant (τm) of 0.62 ms at −10 mV. The kinetics of calcium-current onset and offset are at least two- to threefold faster than those described in other native cells. Combined with other recent data, the results suggest that the rapid kinetics may participate in a fast signaling mode in the goldfish ON-center pathway.

Type
Research Article
Copyright
1998 Cambridge University Press

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