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Arsenazo III transients and calcium current in a normally non‐spiking neuronal soma of crayfish.
Author(s) -
Bruner J,
Czternasty G,
Shimahara T,
Stinnakre J
Publication year - 1986
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1986.sp016098
Subject(s) - absorbance , procambarus clarkii , chemistry , membrane potential , depolarization , hyperpolarization (physics) , biophysics , conductance , calcium , electrophysiology , tetraethylammonium , tetraethylammonium chloride , crayfish , analytical chemistry (journal) , potassium , biochemistry , chromatography , biology , neuroscience , stereochemistry , mathematics , organic chemistry , combinatorics , fishery , nuclear magnetic resonance spectroscopy
Arsenazo III was used to investigate Ca2+ transients in the normally non‐excitable soma of the motor giant neurones of the crayfish Procambarus clarkii. Two kinds of regenerative potentials could be obtained depending on membrane potential conditioning: a fast spike after a pre‐hyperpolarization to ‐90 mV and a slow action potential after a pre‐depolarization to ‐50 mV. Only the second of these was accompanied by an Arsenazo III transient. In voltage‐clamped, somata injected, with tetraethylammonium chloride, an absorbance change could be obtained by pulsing the membrane potential above ‐44 mV. The relationship between absorbance change and potential peaked between 0 and +10 mV then fell off to zero at ca. +150 mV. Changes in light absorbance studied using double‐pulse protocols suggested that the inactivation of Ca2+ entry was predominantly mediated by the intracellular free Ca2+ concentration. External application of 1 mM‐CdCl2 abolished both the absorbance changes and the (Ca2+) inward current. The voltage dependence of this current was similar to that of the absorbance change. For positive membrane potential the current‐voltage relationship showed a voltage‐dependent conductance property, the origin of which is discussed.