The Influence of pH and Methylene Blue on the Pathways of Glucose Utilization and Lactate Formation in Erythrocytes of Man

Abstract

The influence of pH on the contributions of the Embden‐Meyerhof and of the oxidative pentose‐phosphate pathways in the utilization of glucose by human erythrocytes in the presence and absence of methylene blue were determined from yields of 14CO2 and [14C]lactate. In the absence of methylene blue both the NADP+ concentration and the phosphofructokinase are controlling factors. At pH 7.0 the oxidative pentose‐phosphate pathway accounts for nearly one‐half of the metabolic flux. Its contribution nearly vanishes at pH 8.2. In the presence of methylene blue the limitation by the NADP+ concentration disappears. At pH values of 7.4 and below the phosphofructokinase is completely inhibited and is circumvented for the formation of lactate. The limitation of the glucose influx resides in the hexokinase. At pH 8.2 both the Embden‐Meyerhof and the oxidative pentose‐phosphate pathway participate in the metabolic flux, since the inhibition of the phosphofructokinase is released. With methylene blue metabolic pools are formed. They are derived exclusively from the oxidative pentose‐phosphate pathway up to pH 7.5–7.6 and entirely from the Embden‐Meyerhof pathway at pH 8.2. Copyright © 1971, Wiley Blackwell. All rights reserved