AJP - Cell Physiology, Vol 236, Issue 5 255-C261, Copyright © 1979 by American Physiological Society
Cow red blood cells. I. Effect of purines, pyrimidines, and nucleosides in bovine red cell glycolysis
M. J. Seider and H. D. Kim
Cow red cells, under in vitro incubation conditions, exhibit a
comparatively low glycolytic rate of 0.56 +/- 0.05 micromol/(ml cells.h),
with a ratio of lactate formed to glucose consumed of 1.58. It has been
found that this low glycolytic rate can be stimulated 50--60% above the
basal level in the presence of a variety of purine and pyrimidine compounds
including adenosine, inosine, adenine, hypoxanthine, xanthine, and uracil.
In contrast, calf red cells, which have a much higher glycolytic rate,
display no discernible response to these agents. In attempts to elucidate
the mechanism by which this stimulation takes place, both glucose transport
and glycolytic enzyme activities were determined in the presence of these
stimulators. Glucose influx in cow red cells, measured using the glucose
analog 3-O-methyl-glucose, exhibits both a low Km of 117 microM and a Vmax
of 0.38 micromol/(ml cells.min), and is unaltered in the presence of
adenosine. On the other hand, hexokinase, which in normal hemolysates of
cow red cells has an activity of 0.49 +/- 0.03 micromol/(g Hb.min). was
found to be stimulated to 0.73 micromol/(g Hb.min) in the presence of
adenine. Both pyruvate kinase and phosphofructokinase were unaffected by
this compound. These data suggest that certain purines and pyrimidine
compounds may exert their stimulatory effect on hexokinase activity,
resulting in an augmentation of cow red cell glycolysis.
