Localization of alpha 1,2,3-subunit isoforms of Na,K-ATPase in cultured neonatal and adult rat myocardium: the immunofluorescence and immunocytochemical study.

By indirect immunofluorescence and preembedding peroxidase-diaminobenzidine technique the localization of polyclonal and monoclonal antibodies against alpha 1, alpha 2 and alpha 3 isoforms of the Na,K-ATPase were studied in rat myocardium. The alpha 1-subunit was identified predominantly on sarcolemma of cultured myocytes, neonatal, as well as adult cardiocytes. The alpha 2 signal was localized around nuclei of cultured cardiocytes, very weak signals were seen in neonatal and more intense signal, were dispersed throughout the adult myocytes. The alpha 3-subunit immunoreactivity was weak and localized in cell processes connecting individual cultured cells, on sarcolemma and intercalated discs of neonatal cells and very weak in adult working myocytes. Cytochemically demonstrated ouabain resistant Na,K-ATPase localized in junctional sarcoplasmic reticulum may represent alpha 1 isoenzyme which is directly involved in modulation of action potential fluxes.