Assuntos
Ácidos Difosfoglicéricos/sangue , Envelhecimento Eritrocítico , Eritrócitos/metabolismo , 2,3-Difosfoglicerato , Trifosfato de Adenosina/sangue , Alelos , Animais , Ácidos Difosfoglicéricos/genética , Feminino , Ligação Genética , Globinas/genética , Glicólise , Polimorfismo Genético , RatosRESUMO
A major locus (Dpg) with two alleles (d and D) controls erythrocyte 2,3-diphosphoglycerate (DPG) levels in Long-Evans rats and is closely linked to a locus (Hbb) determining a hemoglobin electrophoretic polymorphism. Glycolytic intermediate levels and phosphofructokinase (PFK) kinetic studies suggest that in vivo PFK activity differences underlie the differences in DPG levels. We report here chromatographic and immunologic evidence that rat erythrocyte PFK is composed of two isozymes which elute from DEAE-Sephadex at positions identical to those of the isozymes in platelets and liver, respectively. The percentage of platelet-type PFK is significantly (P less than 0.05) smaller in low-DPG (dd) hemolysates than in DD hemolysates regardless of hemoglobin phenotype. When hemolysates were prepared in a stabilizing buffer, PFK specific activity was significantly (P less than 0.005) higher in DD rats. These data suggest that the PFK kinetic differences may result from alterations in the isozyme composition of active PFK.
Assuntos
Ácidos Difosfoglicéricos/genética , Eritrócitos/enzimologia , Isoenzimas/genética , Fosfofrutoquinase-1/genética , Ratos Endogâmicos/genética , 2,3-Difosfoglicerato , Alelos , Animais , Cromatografia por Troca Iônica , Ácidos Difosfoglicéricos/sangue , Isoenzimas/sangue , Fosfofrutoquinase-1/sangue , Ratos , Ratos Endogâmicos/sangueRESUMO
Glucose utilization through the hexose monophosphate shunt was measured in erythrocytes from fetal sheep, newborn lambs and adult pregnant sheep. Fetal erythrocytes demonstrate dramatically increased glucose oxidation in the presence of the oxidant new methylene blue. This response declines by birth and thereafter until adult sheep erythrocytes show no response. No stimulation was observed in adult sheep red cells under a number of conditions, although when adult sheep red cells were separated according to cell age, young cells were found to respond greatly to new methylene blue. When the rate of glucose oxidation after new methylene blue stimulation is correlated with in vitro glucose-6-phosphate dehydrogenase activity, a highly significant relationship is seen. This suggests that developmental changes in glucose oxidation by sheep red cells may be due to similar changes in glucose-6-phosphate dehydrogenase activity. The relationship also suggests that mature adult erythrocytes may be unable to respond to oxidants because of their low glucose-6-phosphate dehydrogenase activity.
