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  • 1
    Electronic Resource
    Electronic Resource
    Prevention by 7-oxo-prostacyclin of the calcium paradox in rat heart: Role of the sarcolemmal (Na,K)-ATPase (1996)
    Springer
    Molecular and cellular biochemistry 160-161 (1996), S. 257-263 
    Details
    ISSN: 1573-4919
    Keywords: 7-oxo-prostacyclin ; calcium paradox ; sarcolemmal (Na,K)-ATPase ; subsarcolemmal sodium ; subsarcolemmal Na/Ca ratio ; calcium overload of the heart
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract It is demonstrated a fast and significant depression in the sarcolemmal (Na,K)-ATPase activity that occurs as early as 25 sec after the onset of Ca2+ depletion, and participates in the development of Ca2+-paradox in the rat heart. Pretreatment of the animals with 7-oxo-prostacyclin (PG12) 24–48 h prior to the experiment prevented fairly the Ca2+-depletion-induced depression in (Na,K)ATPase activity and the accompanying structural and functional damage to the heart and sarcolemma during Ca2+-depletion as well as the development of Ca2+-paradox during the subsequent Ca2+-repletion. Pretreatment with PGI, was chosen intentionally because previous experiments revealed, that in its late effect the drug is acting via stabilizing the membranes due induction of high activity of (Na,K)-ATPase that has increased affinity to ATP. From results obtained the following may be concluded: If during the phase of Ca2+-deprivation, the capability of heart sarcolemma to maintain sodium extrusion remains preserved, the expected aggravation of Ca2+-overload injury to Ca2+-paradox that would develop during Ca2+-repletion, may be definitely prevented. Sufficiently preserved (Na,K)-ATPase activity, hand in hand with stabilized sarcolemmal structure, may prevent an accumulation of sodium beneath the sarcolemma and consequently also an overexcessive entry of Ca2+ into the myocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00240057
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  • 2
    Electronic Resource
    Electronic Resource
    Cytochemical and immunocytochemical localization of Na,K-ATPase α subunit isoenzymes in the rat heart (1997)
    Springer
    Molecular and cellular biochemistry 176 (1997), S. 107-112 
    Details
    ISSN: 1573-4919
    Keywords: immunogold staining ; adult myocytes ; subsarcolemmal ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract 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 peroxidasediaminobenzidine methods, demonstrated α1 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 α2 isoenzyme, immunoreactivity 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 α3 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 α1 isoenzyme of Na,K-ATPase. A differential as well as unique localization of α subunit isoenzymes of Na,K-ATPase in specific structures of cardiac myocytes may suggest importance in physiological function at these sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006883130242
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  • 3
    Electronic Resource
    Electronic Resource
    Species differences in localization of cardiac cAMP-phosphodiesterase activity: A cytochemical study (1997)
    Springer
    Molecular and cellular biochemistry 173 (1997), S. 183-188 
    Details
    ISSN: 1573-4919
    Keywords: phosphodiesterase ; cytochemistry ; myocardium ; rat ; dog
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The localization of the membrane-bound cyclic 3′,5′-AMP phosphodiesterasein cardiac tissues of both, rat and dog was studied by cytochemical method.40 µm thick slices from glutaraldehyde fixed heart tissue wereincubated in the medium with cAMP as a substrate and Pb ions as a capturemetal of the reaction product. The cAMP-PDE activity in the rat ventriclewas only shown positive on the sarcolemma. Whereas, in canine ventriculartissue the cAMP-PDE activity in cardiomyocytes was shown on the sarcolemma,on the junctional sarcoplasmic reticulum and on subsarcolemmal cisternae.The results confirm differences in the localization of cAMP-PDE in dog andrat heart.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006845513962
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  • 4
    Electronic Resource
    Electronic Resource
    Renaissance of cytochemical localization of membrane ATPases in the myocardium (1995)
    Springer
    Molecular and cellular biochemistry 147 (1995), S. 169-172 
    Details
    ISSN: 1573-4919
    Keywords: membrane ATPases ; cytochemistry ; myocardium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract ATPases of cardiac cells are known to be among the most important enzymes to maintain the fluxes of vital cations by hydrolysis of the terminal high-energy phosphate of ATP. Biochemically the activities of Ca2+-pump ATPase, Ca2+/Mg2+-ecto ATPase, Na+,K+-ATPase and Mg2+-ATPase are determined in homogenates and isolated membranes as well as in myofibrillar and mitochondrial fractions of various purities. Such techniques permit estimation of enzyme activitiesin vitro under optimal conditions without precise enzyme topography. On the other hand, cytochemical methods demonstrate enzyme activityin situ, but not under optimal conditions. Until recently several cytochemical methods have been employed for each enzyme in order to protect its specific activity and precise localization but the results are difficult to interpret. To obtain more consistent data from biochemical and cytochemical point of view, we modified cytochemical methods in which unified conditions for each ATPase were used. The fixative solution (1% paraformaldehyde −0.2% glutaraldehyde in 0.1 M Tris Base buffer, pH 7.4), the same cationic concentrations of basic components in the incubation medium (0.1 M Tris Base, 2mM Pb(NO2)3, 5 mM MgSO4, 5 mM ATP) and selective stimulators or inhibitors were employed. The results reveal improved localization of Ca2+-pump ATPase, Na+−K+ ATPase and Ca2+/Mg2+-ecto ATPase in the cardiac membrane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00944797
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