title: On the release of glycogen phosphorylase from heart muscle: effect of substrate depletion, ischemia and of imipramine.
abstract: The release of glycogen phosphorylase from isolated, perfused rabbit heart was studied after substrate depletion and after global ischemia. The assayed efflux of the enzyme was found to be not only related to alterations in membrane integrity but also to the amount of glycogen in the injured heart tissue. The differential efflux profile of phosphorylase as a constituent of the sarcoplasmic reticulum-glycogenolysis complex in cardiac cells in comparison to cytosolic creatine kinase was found to be more pronounced employing K+-arrested, hypothermically perfused hearts exposed to imipramine (0.4 to 0.6 mM), known for altering specifically membrane integrity. Under these conditions only a rise in the release of creatine kinase occurs, whereas both glycogen content and the efflux of phosphorylase remains uneffected. It is suggested that the metabolical dependence of phosphorylase efflux from the injured heart muscle is of importance for its high sensitivity being a marker of acute heart infarction.
authors.affiliation: Central Institute for Cardiovascular Research, Academy of Sciences of the GDR, Berlin-Buch.
authors.forename: E G
authors.initials: EG
authors.lastname: Krause
authors.forename: A
authors.initials: A
authors.lastname: Härtwig
authors.forename: G
authors.initials: G
authors.lastname: Rabitzsch
mesh_terms: D000818:Animals; D003327:Coronary Disease / Q000201:enzymology*; D003402:Creatine Kinase / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D007099:Imipramine / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007700:Kinetics; D015425:Myocardial Reperfusion; D009206:Myocardium / Q000201:enzymology*; D006005:Phosphorylases / Q000378:metabolism*; D011817:Rabbits; D012016:Reference Values
chemical_list: D007328:Insulin; D006005:Phosphorylases; D003402:Creatine Kinase; D005947:Glucose; D007099:Imipramine