AJP - Endocrinology and Metabolism, Vol 240, Issue 6 645-E648, Copyright © 1981 by American Physiological Society
Alloxan action on glucose metabolism in cultured fibroblasts. II. Effects on pentose-monophosphate shunt and tricarboxylic acid pathways
F. Ishibashi, P. H. Bennett and B. V. Howard
The site of action of alloxan on glucose metabolism has been investigated
using cultured human fibroblasts. Analysis of cell extracts after cell
monolayers were exposed to D-[U-14C]glucose indicated that the initial
stimulation of glucose incorporation by alloxan was observed primarily in
the nucleotide fraction (ribose) with inhibition of lactate production. The
subsequent inhibition of glucose incorporation was observed in the
nucleotide fraction. Assay of 14CO2 production indicated that alloxan
enhanced 14CO2 formation from D-[U-14C]glucose for approximately 10 min,
followed by inhibition. To probe the site of alloxan action, rates of 14CO2
formation from 1- and 6-position labeled [14C]glucose, and [U-14C]pyruvate
were compared. The initial stimulation was observed mainly in
D-[1-14C]glucose oxidation, whereas inhibition was measurable with the
6-position tracer and [14C]pyruvate. The results suggest that alloxan
initially stimulates the pentose-monophosphate shunt and then subsequently
inhibits both the pentose-monophosphate shunt and tricarboxylic acid
pathways.
