AJP - Cell Physiology, Vol 264, Issue 4 C1061-C1065, Copyright © 1993 by American Physiological Society
Increase in cell size underlies neuron-specific temperature acclimation in Aplysia
S. N. Treistman and A. J. Grant
Department of Pharmacology, University of Massachusetts Medical Center, Worcester 01655.
Aplysia californica with similar genetic and environmental backgrounds were
raised under mariculture conditions at either 10 or 20 degrees C.
Determinations of cell surface area using capacitance and visual
measurements indicated that there was an increase in the surface area of
identified neurons. However, this increase was cell specific, occurring
only in certain identified neurons. The amplitude of the early potassium
current (IA) was monitored in identified neurons from the cold- and
warm-reared groups during acute changes in temperature. The response to
acute temperature change differed in the two groups, indicative of partial
temperature acclimation of IA. Cold rearing shifted the acute
temperature-response curve for IA amplitude to color temperatures, compared
with the temperature-response curve for animals reared at warmer
temperatures. This acclimation was related to the increase in surface area
previously noted. Cells showing an increase in IA amplitude in cold-reared
animals also showed an increase in membrane surface area, presumably
associated with an increased number of A-channels, while channel density
was unchanged. There was a small but significant shift in the steady-stage
voltage dependency of inactivation, whereas kinetic properties were
unaffected by rearing temperature.
