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999088458
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Neurons IonicCurrents
68 records
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extracellular Ca2+. We found that currents obtained with 5 mM Ba2+ exhibited
similar voltage dependence of activation to those obtained with 2 mM Ca2+.
Thus the I-V relationships obtained for 5 mM Ba2+ in this study are likely to
be typical of those for Ca2+ currents under more physiological
conditions."p.1433
"Our principal findings were as follows. 1) Neocortical pyramidal cells
express L-, N-, and P-type calcium channels, as well as a component resistant
to specific blockers of those channels. 2) There were no significant
biophysical differences between physiologically defined L-, N-, and P-type
current components. 3) The resistant current had a shorter time to peak
activation, greater percent inactivation, more rapid inactivation kinetics,
and more negative voltage dependence of activation compared with the other
three types."p.1437
"These results of the present studies are limited to the soma and proximal
dendritic membranes due to the dissociation procedure, and voltage-gated
calcium channels appear to be differentially localized to different parts of
the cell (L-type channesl primarily on soma and proximal dendrites and N- and
P-type channels primarily on distal dendrites) (Ahlijanian et al. 1990;
Westenbroek et al. 1990, 1992, 1993). It is therefore likely that N- and
P-type currents contribute relatively more to the Ca2+ influx of the entire
cell than is suggested by our data."p.1441
