title: Different effects of cardioplegic solution HTK during single or intermittent administration.
abstract: Since intermittent cardioplegic reperfusion during an ischemic period may reduce the ischemic stress of the heart at least by lowering myocardial temperature, we compared the post-ischemic recovery of the dog heart following cardioplegia and subsequent continuous ischemia of 1 X 300 minutes at 22 +/- 1 degree C (model 1) and following cardioplegia and subsequent 3 X 100 minutes of ischemia at 17 +/- 1 degree C with intermittent 4-minute cardioplegic reperfusion every 100 minutes (model 2). The parameters of post-ischemic recovery were the cardiac O2 consumption per beat at work (MVO2-E0): HR), the stability of cardiac rhythm, the left ventricular content of high-energy phosphates, and ultrastructure. Solution HTK with a magnesium concentration of 9 mM/L, in clinical use up to the beginning of 1984, resulted in a significantly better post-ischemic recovery in model 1, despite about 40% lesser ischemic stress in model 2. A reduction of Mg concentration from 9 to 4 mM/l, as in the HTK solution clinically tested since February 1984, did facilitate the post-ischemic recovery in model 1 as indicated by the stability of cardiac rhythm but led to a significant improvement of all parameters of recovery in model 2. Moreover, recovery in model 2 after reduced Mg was also clearly better than in model 1 corresponding to the lesser ischemic stress. The parameters myocardial O2 consumption (MVO2) and potassium loss during HTK perfusion containing 9 and 4 mM/l, respectively, gave indications of specific membrane labilizing effects of Mg in the cardioplegic solution HTK.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004562:Electrocardiography; D006324:Heart Arrest, Induced / Q000379:methods*; D006329:Heart Conduction System / Q000187:drug effects; D006639:Histidine / Q000494:pharmacology*; D008274:Magnesium / Q000494:pharmacology*; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010725:Phosphocreatine / Q000378:metabolism; D011803:Quinine / Q000494:pharmacology*
chemical_list: D000227:Adenine Nucleotides; D000889:Anti-Arrhythmia Agents; D010725:Phosphocreatine; D006639:Histidine; D000255:Adenosine Triphosphate; D011803:Quinine; D008274:Magnesium