title: Effects of cardioplegia on myocardial metabolism during hypothermic ischemia--components and mode of administration.
abstract: Isolated rat heart preparations were used to determine the effect of cardioplegia on myocardial metabolism during profound hypothermic (15 degrees C) ischemia. The hearts were grouped according to the components of cardioplegia and the mode of administration. The six groups were normokalemic (GI), calcium-containing hyperkalemic (GII), calcium-free hyperkalemic (GIII) and single dose (A), multidose (B). Following 120 min of ischemia, tissue ATP decreased from 25.4 +/- 2.2 to 10.3 +/- 2.7, 3.9 +/- 2.4, 4.1 +/- 1.2, 15.5 +/- 3.2, 14.5 +/- 2.4 and 20.0 +/- 2.7 (I-A vs II-A p less than 0.005, I-A vs III-A p less than 0.005, I-B vs III-B p less than 0.05, II-B vs III-B p less than 0.005), and tissue lactate increased from 9.6 +/- 1.5 to 163.4 +/- 12.0, 174.1 +/- 13.5, 166.8 +/- 21.3, 99.1 +/- 8.3, 102.6 +/- 12.2 and 83.5 +/- 9.3 (I-B vs III-B p less than 0.02, II-B vs III-B p less than 0.02) mumol/dry wt g, in GI-A, GII-A, GIII-A, GI-B and GII-B, respectively. The results of this study suggests that (1) potassium cardioplegia in a single dose does not prevent degradation of high energy phosphate (HEP) in the hypothermic arrested heart, (2) though multidose cardioplegia is effective in preserving HEP during ischemia, the extent of its effects varies with the composition, and (3) the omission of calcium is beneficial in GIK cardioplegia in terms of preserving HEP at the end of ischemia.
mesh_terms: D000227:Adenine Nucleotides / Q000378:metabolism; D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D005947:Glucose / Q000008:administration & dosage; D005958:Glucosephosphates / Q000378:metabolism; D006324:Heart Arrest, Induced; D066298:In Vitro Techniques; D007328:Insulin / Q000008:administration & dosage; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D010725:Phosphocreatine / Q000378:metabolism; D011188:Potassium / Q000008:administration & dosage; D017680:Potassium Compounds; D051381:Rats
chemical_list: D000227:Adenine Nucleotides; D005958:Glucosephosphates; D007328:Insulin; D007773:Lactates; D017680:Potassium Compounds; C030396:glucose-insulin-potassium cardioplegic solution; C018369:potassium cardioplegic solution; D010725:Phosphocreatine; D019344:Lactic Acid; D000249:Adenosine Monophosphate; D000255:Adenosine Triphosphate; D005947:Glucose; D011188:Potassium; D002118:Calcium