Methemoglobin formation and reduction in canine erythrocytes characterized by inherited high Na+, K(+)-ATPase activity with normal and high glutathione concentrations.
The methemoglobin formation and methemoglobin reduction in canine erythrocytes characterized by inherited high potassium (K+) and normal reduced glutathione concentrations (HK-low GSH cells) were compared with those in canine erythrocytes with inherited high K+ and high GSH concentrations (HK-high GSH cells) and normal canine erythrocytes with low K+ and low (= normal) GSH concentrations (LK-low GSH cells). The rate of methemoglobin formation induced by sodium nitrite (NaNO2) was in the order; LK-low GSH > HK-low GSH > HK-high GSH cells, and the difference among groups was significant at 7 and 15 min. Methemoglobin reduction in a medium containing glucose occurred rapidly in both HK-high GSH and HK-low GSH cells, and the rate of reduction was 1.7-fold higher than in LK-low GSH cells. Accumulation of pyruvate equivalent to the amount of methemoglobin reduced indicated that methemoglobin was predominantly reduced by NADH-methemoglobin reductase coupled to glycolysis. HK-low GSH cells showed an increased glycolytic rate and high pyruvate kinase activity similar to the levels in HK-high GSH cells. It is therefore evident that HK-low GSH cells offer greater protection against oxidation of hemoglobin to methemoglobin than LK-low GSH cells because of the increased glycolytic rate in HK-low GSH cells attributable to high pyruvate kinase activity in these cells.
Ogawa
E
E
Department of Pathology II, Azabu University, Kanagawa, Japan.
Horii
Y
Y
Honda
M
M
Takahashi
R
R
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D042966:Cytochrome-B(5) Reductase / Q000097:blood; D004285:Dogs / Q000097:blood*; D004912:Erythrocytes / Q000378:metabolism*; D005978:Glutathione / Q000097:blood*; D006019:Glycolysis; D007700:Kinetics; D007773:Lactates / Q000097:blood; D008706:Methemoglobin / Q000096:biosynthesis / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood* / Q000235:genetics; D013045:Species Specificity
D001786:Blood Glucose; D007773:Lactates; D008706:Methemoglobin; D042966:Cytochrome-B(5) Reductase; D011770:Pyruvate Kinase; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione