Glucose transport by isolated plasma membranes of the bovine blood
-brain barrier.
Lee, Wha-Joon, D. R. Peterson, E. J. Sukowski, and R. A. Hawkins.
Department of Physiology and Biophysics
APStracts 3:0397C, 1996.
Luminal and abluminal endothelial plasma membrane vesicles were
isolated from bovine cerebral microvessels, the site of the blood
-brain barrier. Glucose transport across each membrane was measured
using a rapid filtration technique. Glucose transport into luminal
vesicles occurred by a stereospecific energy-independent transporter
(Km 10.3 2.8 mM, SE, and Vmax 8.6 2.0 nmol(mg protein-1(min-1).
Kinetic analysis of abluminal vesicles also showed a transport system
with similar characteristics to the luminal transporter (Km 12.5 2.3
mM and Vmax 10.0 1.0 nmol(mg protein-1(min-1). These functional,
facilitative glucose transporters were symmetrically distributed
between the luminal and abluminal membrane domains, providing a
mechanism for glucose movement between blood and brain. The studies
also revealed a Na-dependent transporter on the abluminal membrane
with a higher affinity and lower capacity than the facilitative
transporters (Km 130 20 M and Vmax 1.59 0.44 nmol(mg protein-1(min
-1). The abluminal Na-dependent glucose transporter is in a position
to transport glucose from the brain extracellular fluid into the
endothelial cells of the blood-brain barrier. The functional
significance of its presence there remains to be determined.
Received 31 July 1996; accepted in final form 4 December 1996.
APS Manuscript Number C430-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 31 December 1996