Key result
Increasing diastolic volume and developed tension in a blood-perfused dog heart resulted in a net loss of myocardial potassium, whereas low tension was associated with potassium gain.
Why the study?
Does increasing preload alter myocardial potassium balance in a dog heart model?
Does increasing preload alter myocardial potassium balance in a dog heart model?
Increasing myocardial wall tension via increased preload leads to a net loss of myocardial potassium in a dog heart model.
May link increased preload to myocardial K+ loss in dogs; hypothesis-generating for human HF or arrhythmia risk.
Experiments were carried out to determine the effect of changing preload on myocardial potassium balance. A blood-perfused dog heart was employed. Changes in the pressure recorded from a balloon in the left ventricle were assumed to reflect directional changes in myocardial wall tension. Developed tension was altered by changing the volume of the balloon. Net potassium balance was calculated as the product of the coronary A-V plasma potassium difference and coronary plasma flow. When the ventricle was developing little tension, it usually gained potassium. When diastolic volume and thus developed tension was increased, a net loss of myocardial potassium occurred. In some experiments the hemodynamic response of the ventricle to the increase in diastolic volume suggested that the contractility of the heart was increasing while the heart was losing potassium.
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Gilmore et al. (1968) studied this question. Changing preload (diastolic volume) vs. Low tension/baseline was evaluated on Myocardial potassium balance. Increasing diastolic volume and developed tension in a blood-perfused dog heart resulted in a net loss of myocardial potassium, whereas low tension was associated with potassium gain.
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