1992 Fiscal Year Final Research Report Summary
Ischemia induced ventricular arrhythemias in the presence of hypokalemia
| Project/Area Number |
02670400
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Circulatory organs internal medicine
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| Research Institution | Nagasaki University |
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Principal Investigator |
YANO Katsusuke Nagasaki University 3rd Dept of Int Med Professor of Medicine, 医学部, 教授 (50039864)
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| Co-Investigator(Kenkyū-buntansha) |
MITSUOKA Takao Nagasaki University 3rd Dept of Int Med Assistant, 医学部, 助手
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| Project Period (FY) |
1990 – 1992
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| Keywords | chronic hypopotassemia / extracellular potassium / ventricular arrhythmias / coronary occlusion / coronary reperfusion / effective refractory period / intraventricular conduction time |
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| Research Abstract |
During acute ischemia, myocardial cells release potassium ion that accumulate in the extracellular space because of reduced blood flow. The resulting altered potasslum gradients induce injury currents and are accompanied by typical electrophysiologic changes, which predispose the heart to ventricular arrhythmias. The present study was designed to examine changes in extracellular potassium during coronary occlusion and subsequent reperfusion, susceptibility of the heart to ventricular arrhythmias and electrophysiologic properties of the heart during myocardial ischemia in the dog with chronic hypopotassemia. To produce chronic hypopotassemia 20 dogs were fed special low-potassium diet and intramuscular administration (once a day) of furosemide (10 mg) and to produce normopotassmia 20 dog were fed ordinary diet for 4 weeks. Programmed ventricular stimulation was performed for induction of ventricular arrhythmias and for determination of effective refractory period and intraventricular conduction time. Extracellular potassium activity was recorded at normal and ischemic area of the heart during occlusion of the anterior descending coronary artery (LAD) and subsequent reperfusion. Extracellular potassium in the ischemic area of the heart was progressively increased during coronary occlusion and rapidly reduced after coronary reperfusion in the hypopotassemia and normopotassemia groups. The magnitude of increase in extracellular potassium was not significantly different between the two groups. Incidence of ventricular arrhythmias, dispersion of effective refractory period and intraventricular conduction delay in the ischemic area of the heart were greater in the dog with hypopotassemia than in the dog with normopotassemla. In conclusion, changes in extracellular potassium during coronary artery occlusion and subsequent reperfusion have important roles in the genesis of the ventricular arrhythmias in the presence of chronic hypopotassemia.
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