The subunit proportions and kinetic properties of 6-phosphofructo-1-kinase isozymes from rat heart atria and ventricle progressively change during aging.
Relative to 2-3 month rats, total 6-phosphofructo-1-kinase (PFK) activity in heart atria from 12 month rats declined 31%; but, by 24 months it was decreased by only 13%. PFK activities from 12 and 24 month ventricles relative to the 2-3 month rats were decreased by 40% and 30%, respectively. This change in PFK activity in each heart region was associated with alterations of subunit composition. In heart atria from 12 and 24 month rats when compared to 3 month rats, the levels of L-type subunit were not significantly different; but the levels of the M-type subunit were decreased by 43% and 38%, respectively. With respect to levels in 2-3 month atria, the C-type subunit in 12 month atria decreased by 27%; and at 24 months it increased by 31%. Making the same comparison for the heart ventricle at 12 and 24 months, L-type subunit decreased by 30% and 24% respectively; M-type subunit decreased by approximately 47%; and the C-type subunit increased 1.9 and 4.7 fold, respectively. These age-related changes of subunit composition in atrial and ventricular PFK isozyme pools led to changes in their kinetic and regulatory properties suggesting that the aged rat could exhibit a diminished capacity to produce ATP from glucose.
Mhaskar
Y
Y
Department of Pharmacology, Southern Illinois University School of Medicine, Springfield.
Dunaway
G A
GA
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology; D006325:Heart Atria / Q000201:enzymology*; D006352:Heart Ventricles / Q000201:enzymology*; D007527:Isoenzymes / Q000302:isolation & purification* / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D009928:Organ Specificity; D010732:Phosphofructokinase-1 / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains / Q000378:metabolism
D007527:Isoenzymes; D010732:Phosphofructokinase-1