title: Myocardial cell damage and breakdown of cation homeostasis during conditions of ischaemia and reperfusion, the oxygen paradox, and reduced extracellular calcium.
abstract: Enzyme release from perfused rat heart was determined under various conditions of injury. In analogous experiments, intracellular cation concentrations were measured using ion-selective microelectrodes. Under appropriate conditions, the inhibition of mitochondrial and/or glycolytic ATP production led to a decrease in the release of enzymes. During ischaemia or the oxygen paradox, the sarcosolic Ca2+ concentration was highly elevated; reperfusion or reoxygenation was followed by a drastic enzyme release. This was also found to be true under the conditions of an increased permeability brought about by a reduced extracellular Ca2+ concentration of 0.1 mmol/l. The intracellular pH under all conditions of injury was only moderately decreased. The sarcosolic Na+ concentration was markedly increased whereas the K+ concentration was decreased. The critical Ca2+ concentration of the sarcosol beyond which cell damage and enzyme release are inducible was assumed to be in the range between 10 and 32 mumol/l. The driving force of the Na+/Ca2+ exchange reaction of the sarcolemma is discussed in relation to recovery from hypoxic injury and the potential for avoiding cell damage.
authors.affiliation: Abteilung Klinische Biochemie, Medizinische Hochschule Hannover, FRG.
authors.forename: F
authors.initials: F
authors.lastname: Diederichs
authors.forename: H
authors.initials: H
authors.lastname: Wittenberg
authors.forename: U
authors.initials: U
authors.lastname: Sommerfeld
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002412:Cations; D003327:Coronary Disease / Q000378:metabolism / Q000503:physiopathology*; D003402:Creatine Kinase / Q000378:metabolism; D005110:Extracellular Space / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008564:Membrane Potentials; D008839:Microelectrodes; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology*; D010100:Oxygen / Q000378:metabolism; D051381:Rats; D012508:Sarcolemma / Q000378:metabolism
chemical_list: D002412:Cations; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D003402:Creatine Kinase; D010100:Oxygen; D002118:Calcium