Distribution of extracellular potassium and electrophysiologic changes during two-stage coronary ligation in the isolated, perfused canine heart.
We studied the relation between [K+]o and the electrophysiologic changes during a "Harris two-stage ligation," which is an occlusion of a coronary artery, preceded by a 30-minute period of 50% reduction of flow through the artery. This two-stage ligation has been reported to be antiarrhythmic. Local direct current electrograms and [K+]o signals from up to 48 intramural sites were simultaneously recorded in isolated, perfused dog hearts. A second period of one-stage ligation was compared with a consecutive two-stage ligation because reproducibility in [K+]o and electrophysiologic changes are established only after the first period of ischemia. In control experiments, no difference was found between the second and third period of one-stage ligation in the electrophysiologic changes and in increases in [K+]o. After complete occlusion during two-stage ligation, activation block in the ischemic tissue occurred about 6 minutes earlier than during one-stage ligation, but the average potassium concentration at which block occurred was identical. This [K+]o during total ischemia was achieved earlier during two-stage ligation than during one-stage ligation. No indication was found for a large decrease of intracellular potassium content during the period of low flow perfusion. Early activation block may explain the previously reported reduced incidence of ventricular fibrillation during two-stage ligation.
Coronel
R
R
Department of Clinical and Experimental Cardiology, Academic Medical Centre, Amsterdam, The Netherlands.
Fiolet
J W
JW
Wilms-Schopman
J G
JG
Opthof
T
T
Schaapherder
A F
AF
Janse
M J
MJ
D000818:Animals; D003251:Constriction, Pathologic; D003326:Coronary Circulation; D003327:Coronary Disease / Q000503:physiopathology; D003331:Coronary Vessels; D004285:Dogs; D004594:Electrophysiology; D005110:Extracellular Space / Q000378:metabolism*; D006321:Heart / Q000502:physiology*; D066298:In Vitro Techniques; D008026:Ligation; D009206:Myocardium / Q000378:metabolism*; D009994:Osmolar Concentration; D010477:Perfusion; D011188:Potassium / Q000378:metabolism*; D014018:Tissue Distribution
D011188:Potassium