title: Sarcolemmal Na+-Ca2+ exchange during the development of genetically determined cardiomyopathy.
abstract: The UM-X7.1 myopathic and control hamsters at 40, 120 and 280 days of age were employed for the examination of heart sarcolemmal Ca2+-transport activities. Na+-dependent Ca2+ uptake activities were significantly depressed in myopathic animals at 120 and 280 days of age in comparison to the control values. No difference in Na+-induced Ca2+ release activities was found between control and experimental sarcolemmal vesicles. ATP-dependent Ca2+ binding and Ca2+-stimulated, Mg2+ ATPase activities were depressed in the experimental animals at 120 and 280 days of age. Similar alterations in the sarcolemmal Na+-dependent Ca2+ exchange and Ca2+-pump activities were seen upon treating the control hamsters with 40 mg/kg isoproterenol for 24 hr. It is suggested that a depression in the sarcolemmal Ca2+ transport activities may contribute to the development of intracellular Ca2+ overload in the genetically determined cardiomyopathy in hamsters and such a defect may be due to excessive amount circulating catecholamines in these animals.
mesh_terms: D000375:Aging; D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D009202:Cardiomyopathies / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D007545:Isoproterenol / Q000494:pharmacology; D008647:Mesocricetus; D009206:Myocardium / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism* / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D007545:Isoproterenol; D002118:Calcium