作者: Michihiko Tada , Madeleine A. Kirchberger , Doris I. Repke , Arnold M. Katz
DOI: 10.1016/S0021-9258(19)42237-0
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摘要: Abstract The effects of an adenosine 3':5'-monophosphate (cyclic AMP)-dependent protein kinase on Ca2+-activated triphosphatase (ATPase) activity and calcium uptake canine cardiac microsomes were examined. microsomes, which represent enriched preparation fragmented sarcoplasmic reticulum, preincubated with varying concentrations cyclic AMP-dependent or AMP both in the presence Mg2+ ATP. ATPase determined oxalate various Ca2+. Ionized Ca2+ maintained buffers containing CaCl2 ethylene glycol bis (β-aminoethyl ether)-N,N'-tetraacetic acid. initial rates increased 2 to 3 times following 10-min preincubation 1 µm AMP. Pretreatment absence caused a lesser degree stimulation, whereas pretreatment alone had no detectable effect. Stimulation by was dependent concentration: maximal stimulation seen at approximately 10-6 m apparent half-maximal 10-7 m. Marked concentration µm. stoichiometric coupling moles taken up per mole ATP hydrolyzed, stimulatory could be shown after washed buffered 50 mm KCl. These findings indicate that can increase rate transport reticulum without altering efficiency pump. This effect may account for abbreviation systole is agents, like epinephrine, production, resulting alterations distribution within myocardial cell responsible, least part, augmentation contractility.