Decrease in the ratio of high- to low-affinity isozymes of (Na+ +K+)-ATPase during the development of rat cardiac ventricles.
The ratio of (Na+ +K+)-ATPase (EC 3.6.1.3.)isoforms with high and low affinity for cardiac glycosides was studied in heart preparations from neonatal, 3-month and 6-month old Wistar rats. Biphasic ouabain inhibition curves of (Na+ +K+)-ATPase activity indicated that the relative contribution of the high-affinity process decreased from 34% at 9 days to 23% at 3 months and to 10% at 6 months. Scatchard plots for [3H]ouabain binding were curvilinear and indicated that the relative contribution of the high-affinity sites (Kd = 0.1-0.25 microM) decreased by about one-half between 3 months (19-24%, N = 2) and 6 months (9-11%, N = 2).
Departamento de Farmacologia Básica e Clínica, ICB, Universidade Federal do Rio de Janeiro, Brasil.
C M
CM
Alves
C L
CL
Silva
G M
GM
Moura
F
F
Noël
D000367:Age Factors; D000818:Animals; D001665:Binding Sites; D006352:Heart Ventricles / Q000187:drug effects* / Q000254:growth & development; D007527:Isoenzymes / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D007527:Isoenzymes; D000254:Sodium-Potassium-Exchanging ATPase