Cytochemical and immunocytochemical localization of Na,K-ATPase alpha subunit isoenzymes in the rat heart.
In order to understand the functional significance of Na,K-ATPase subunits as well as their isoenzymes, a precise subcellular localization of these in the myocyte is a crucial prerequisite. Cytochemical, immunofluorescence, preembedding immunogold and horse radish peroxidase-diaminobenzidine methods, demonstrated alpha 1 isoenzyme immunoreactivity on the sarcolemma, T-tubules and the subsarcolemmal cisterns of the adult cardiac myocytes. Cytochemically, ouabain resistant Na,K-ATPase precipitate was localized only in the subsarcolemmal cisterns and junctional sarcoplasmic reticulum. For alpha 2 isoenzyme, immuno-reactivity was demonstrated on the sarcolemma as well as in all areas of the myocytes in particularly a close proximation to the sarcoplasmic reticulum and microsomes. For alpha 3 isoenzyme, only a weak insignificant signal was noted on the sarcolemma, intercalated disc and sarcoplasm. It is suggested that cytochemical ouabain resistant precipitate present in subsarcolemmal cisterns and junctional sarcoplasmic reticulum represent alpha 1 isoenzyme of Na,K-ATPase. A differential as well as unique localization of alpha subunit isoenzymes of Na,K-ATPase in specific structures of cardiac myocytes may suggest importance in physiological function at these sites.
Slezák
J
J
Institute for Heart Research, Slovak Academy of Sciences, Bratislava, Slovak Republic.
Schulze
W
W
Okruhlicová
L
L
Tribulová
N
N
Singal
P K
PK
D000818:Animals; D018929:Cell Culture Techniques; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000378:metabolism*; D008854:Microscopy, Electron; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012508:Sarcolemma / Q000201:enzymology; D012519:Sarcoplasmic Reticulum / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D007527:Isoenzymes; D000254:Sodium-Potassium-Exchanging ATPase