The responses of pacemaker and nonpacemaker Aplysia neurons to voltage clamp commands of less than 200 msec duration are essentially identical. For moderate depolarizing commands there is an early inward transient current followed by a late outward current and an outward tail current when the membrane is clamped back to resting potential. On long (1–2 sec) commands in pacemakers there is a marked sag in the late current and an inward tail current. Etail, the potential of the membrane at which there is no net current flow under the conditions prevailing at the end of the clamp, shifts from about -9.0 mv on short commands to +5.0 mv on long commands. In contrast there is no marked sag of the late current or inward tail current on long commands in nonpacemakers, and Etail is near -9.0 mv for both short and long commands. The current sag and shift in Etail can be ascribed to a decreased conductance (presumably to K+) at the end of the long as compared to the short command in half of the pacemaker neurons. In the remaining cells the essential difference from nonpacemakers appears to be either a greater restricted extracellular space or a more active potential-dependent electrogenic Na+ pump in pacemakers.
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1 October 1969
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October 01 1969
Differences between Pacemaker and Nonpacemaker Neurons of Aplysia on Voltage Clamping
Barbara O. Alving
Barbara O. Alving
From the Laboratory of Neurophysiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland 20014
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Barbara O. Alving
From the Laboratory of Neurophysiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland 20014
Received:
March 27 1969
Online ISSN: 1540-7748
Print ISSN: 0022-1295
Copyright © 1969 by The Rockefeller University Press
1969
J Gen Physiol (1969) 54 (4): 512–531.
Article history
Received:
March 27 1969
Citation
Barbara O. Alving; Differences between Pacemaker and Nonpacemaker Neurons of Aplysia on Voltage Clamping . J Gen Physiol 1 October 1969; 54 (4): 512–531. doi: https://doi.org/10.1085/jgp.54.4.512
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