Studies on the ontogenesis of the different isoenzymes of Na+, K+-ATPase in rat brain in vivo and in vitro in relation to their regulation and cellular localisation.
Na+,K+ ATPase isoenzyme activities (alpha(+)-high ouabain affinity; alpha low ouabain affinity) were investigated in developing rat brain in vivo and in whole rat brain reaggregating cultures in vitro. The perinatal profile of the two isoenzyme forms in vivo revealed that, although alpha activity predominates in immature (P14.5-P16) brain, the activity alpha(+) form increases more increases more rapidly such that it is predominant at birth in both cerebellum and forebrain. No regional variation in the proportional activities of the two isoenzyme forms was seen perinatally to explain the previously reported, differential sensitivity of the cerebellar alpha isoenzyme to neonatally induced hypothyroidism. Whole rat brain reaggregating cultures seeded at P16 show a normal development of Na+,K+ ATPase isoenzyme activity if grown for 14 days in a serum supplemented medium (S+). Cultivation of whole rat brain reaggregates in serum deprived medium (S-) leads to a retarded development of alpha isoenzyme activity possibly due to the absence of T3 from the medium. Hormonally-induced changes in the development of the brain Na+, K+-ATPase isoenzymes are discussed in relation to their possible function and cellular localization.
D000818:Animals; D001921:Brain / Q000201:enzymology / Q000254:growth & development*; D007527:Isoenzymes / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014018:Tissue Distribution
D007527:Isoenzymes; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase