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FREQUENCY‐DEPENDENT CHANGES IN THE CARDIAC SARCOLEMMAL ATPASE
Author(s) -
KHATTER J.C.,
PRASAD K.
Publication year - 1977
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1977.tb07484.x
Subject(s) - contractility , stimulation , medicine , endocrinology , sarcolemma , chemistry , atpase , contraction (grammar) , biology , myocyte , enzyme , biochemistry
1 Effects of various frequencies (0.25, 0.5, 1.0, 1.5 or 2.0 Hz) of stimulation for various durations (2, 5, 10 or 15 min) on the contractile force of trabecular or papillary muscles of dog myocardium were investigated. 2 Effects of various frequencies (0, 0.25, 0.5, 1.0, 2.0 Hz) of various stimulus strengths (0.5, 1, 10 V) for various durations (2, 5, 10 or 15 min) on the Mg 2+ ‐dependent Na + ‐K + ‐adenosinetriphosphatase (ATPase) of isolated sarcolemmal fraction of dog myocardium were determined. 3 There was a frequency‐dependent increase in the contractility and inhibition of the Na + ‐K + ‐ATPase within 2 minutes. 4 Frequency‐dependent increase in the contractility and inhibition of Na + ‐K + ‐ATPase decreased as the duration of stimulation was increased. 5 The diminution in the inhibition of ATPase was associated with a decrease in the contractility with prolonged stimulation. 6 These results suggest that the frequency‐dependent increase in the myocardial contractility might be mediated through an inhibition of the sarcolemmal ATPase.