AJP - Renal Physiology, Vol 245, Issue 2 227-F231, Copyright © 1983 by American Physiological Society
Fluidity of brush border and basolateral membranes from human kidney cortex
C. Le Grimellec, S. Carriere, J. Cardinal and M. C. Giocondi
The physical state of lipids in brush border and basolateral membrane
vesicles prepared from normal human kidney cortex was investigated by
fluorescence polarization and electron spin resonance. At physiologic
temperature, lipids were significantly less ordered, i.e., more fluid, in
basolateral than in brush border membranes. This difference was also
observed using corresponding liposomes made from total lipid extracts. For
both brush border and basolateral membranes, temperature-dependent
experiments revealed the existence of a broad thermotropic transition
extending approximately from 20 to 42 degrees C. These data are interpreted
to indicate that plasma membranes from human kidney cortex function
physiologically at the upper critical temperature of a transition that
probably corresponds to a liquid crystalline-to-gel lipid phase separation.
