Microperfusion studies of normal retinal vessels. D-glucose transport

An experimental model was developed to study the permeability of individual retinal vessels in vitro using microperfusion techniques adapted from the kidney tubule studies. Inulin was used as the reference tracer and D-glucose as the test tracer. We found a concentration dependent flux of D-glucose from lumen to bath that increased as D-glucose concentrations in the lumen rose. The flattening of the hyperbolic curve at the higher D-glucose concentrations in the lumen appears consistent with the Michaelis-Menten equation (Km = 6 x 10(-3) M).