The saturation characteristics of glucose transport in bovine retinal pigment epithelium.
OBJECTIVE
To study the saturation characteristics of the glucose transport across the bovine retinal pigment epithelium(RPE).


METHODS
The bovine RPE preparations were munted with a modified Ussing chamber. The L-[3H]-glucose and 3-O-methyl-D-[14C]-glucose fluxes across the RPE from the choroid to retina were studied at different glucose concentrations.


RESULTS
The glucose transport was found to be stereospecific, with 3-O-methyl-D-glucose (MDG) being transported about three times faster than L-glucose. The glucose transport showed typical saturation characteristics in Michaelis-Menten fashion. The Vmax and the Km of corrected MDG were 2452 nmol cm-2h-1 and 30.8 mM respectively. It was shown that the glucose transport system was saturated at 61.6 mM.


CONCLUSIONS
The saturation characteristics of the corrected MDG flux suggested that the capacity of glucose transport through the bovine RPE is immense.
To
C H
CH
Laboratory of Ocular Physiology and Biochemistry, Department of Optometry and Radiography, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Cheung
K K
KK
Chiu
S H
SH
Lai
H M
HM
Lung
K S
KS
D019325:3-O-Methylglucose / Q000378:metabolism; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002417:Cattle; D002829:Choroid / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D010786:Photoreceptor Cells / Q000378:metabolism; D010857:Pigment Epithelium of Eye / Q000378:metabolism*; D012160:Retina / Q000378:metabolism
D019325:3-O-Methylglucose; D005947:Glucose