AJP - Regulatory, Integrative and Comparative Physiology, Vol 256, Issue 1 49-R55, Copyright © 1989 by American Physiological Society
Differential effects of cooling in hibernator and nonhibernator cells: Na permeation
Z. Q. Zhou and J. S. Willis
Department of Physiology and Biophysics, University of Illinois, Urbana 61801.
Unidirectional Na influx is less inhibited by cooling in guinea pig red
blood cells than in ground squirrel cells. To isolate the source of this
difference, component pathways of 24Na entry were estimated by use of
selective inhibitors (ouabain, bumetanide, amiloride). Amiloride slightly
inhibited influx in ground squirrel cells at every temperature between 37
and 5 degrees C. Amiloride did not consistently inhibit Na influx at 37
degrees C in guinea pig cells but caused a 44% inhibition at 25 degrees C
and a 35% inhibition at 5 degrees C. Cytoplasmic acidification caused an
increase in amiloride-sensitive influx in guinea pig cells, which was
greater at 20 degrees C than at 37 degrees C; cytoplasmic acidification
decreased amiloride-sensitive Na influx in ground squirrel cells at 37
degrees C and had no effect at 20 degrees C.
