title: Dissociation of myocardial sodium and potassium alterations in mild versus severe ischemia.
abstract: To determine the relative influence of two levels of ischemia on myocardial cation and water composition as well as cardiac function, intact anesthetized dogs were studied for 1 h using a balloon-tip catheter in the proximal left anterior descending coronary artery. Hemodynamic studies in group A revealed a diminished ejection fraction during mild and severe ischemia associated, respectively, with a 36% and 74% decline in transmural coronary flow. Left ventricular end diastolic pressure rose only after severe ischemia. Greater accumulation of sodium and water and loss of K+ in ischemic tissue was observed in animals with severe ischemia. In group B, intracellular cations and water were estimated on the basis of 51Cr-labeled EDTA distribution. The extracellular space was unaltered at either level of ischemia. During mild ischemia, cell Na+ and H2O were enhanced in the inner and outer layers of myocardium. Despite a 25% reduction in subendocardial blood flow by the labeled microsphere technique, K+ content was normal. After severe ischemia, cell K+ was reduced in inner and outer layers. However, the increase of cell Na+ content substantially exceeded K+, suggesting a major effect on the sodium pump or cell permeability.
mesh_terms: D000818:Animals; D001693:Biological Transport, Active; D001834:Body Water / Q000378:metabolism; D003326:Coronary Circulation; D003327:Coronary Disease / Q000378:metabolism*; D004285:Dogs; D006321:Heart / Q000502:physiology*; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012039:Regional Blood Flow; D012964:Sodium / Q000378:metabolism*
chemical_list: D012964:Sodium; D011188:Potassium