title: ATP produced by myocardial sarcolemmal-bound creatine kinase is not preferentially used by the Na+ pump.
abstract: It has been proposed (Grosse et al. (1980) Biochim. Biophys. Acta 603, 142-156) that membrane-bound creatine kinase and the ATP-dependent Na+ pump form a functional complex in cardiac sarcolemmal vesicles. In this model ADP produced at Na+ pump sites would be rephosphorylated by the creatine kinase for preferential delivery back to the Na+ pump. We have reexamined this hypothesis and find that under some conditions active Na+ transport can be stimulated by ATP produced by sarcolemmal creatine kinase. However, the characteristics of this stimulation are no different than stimulation produced by an added soluble ATP-regenerating system (phosphoenolpyruvate/pyruvate kinase). Thus, we are unable to detect coupling between the Na+ pump and sarcolemmal creatine kinase.
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D003402:Creatine Kinase / Q000378:metabolism*; D004073:Digitoxigenin / Q000494:pharmacology; D004285:Dogs; D009206:Myocardium / Q000201:enzymology*; D010725:Phosphocreatine / Q000494:pharmacology; D012508:Sarcolemma / Q000201:enzymology*; D012964:Sodium / Q000378:metabolism*
chemical_list: D010725:Phosphocreatine; D004073:Digitoxigenin; D000255:Adenosine Triphosphate; D012964:Sodium; D003402:Creatine Kinase