Reciprocal ST segment changes reproduced in burn-induced subepicardial injury model in bullfrog heart

Figures

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  Fig. 1.. Induction of subepicardial burn injury in bullfrog heart. (A) To induce subepicardial burn injuries in some frog hearts (n=6), a heated glass capillary tube was repeatedly placed on the ventricular wall adjacent to the ECG recording. (B) In the other frog hearts (n=6), burn injuries were similarly induced on the side opposite to the ventricle where the electrocardiogram (ECG) electrode was placed.

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  Fig. 2.. Changes in electrocardiogram (ECG) before and after burn injury. (A) ECG changes before (top) and after burn injuries were induced on the ventricular surface (bottom). (B) ECG changes before (top) and after burn injuries were induced on the opposite side of the ventricle (bottom).

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  Fig. 3.. Mechanisms of reciprocal ST segment changes in subepicardial burn injury model. (A) Mechanisms of ST segment elevation. When myocardial injury was induced on the same side of the ventricular surface where the ECG recording electrode was placed (a), the “currents of injury” (white arrows) that arose from the damaged subepicardium flowed away from the electrode. Therefore, the electrocardiogram (ECG) vector during the diastolic phase showed a negative deflection from the isoelectric line (b, arrows), making the ST segment appear elevated during the systolic phase (gray waveform). (B) Mechanisms of ST segment depression. When myocardial injury was induced on the opposite side of the ventricle where the ECG recording electrode was placed (a), the “currents of injury” (white arrows) flowed towards the electrode. In such cases, the ECG vector during the diastolic phase showed a positive deflection from the isoelectric line (b, arrows), making the ST segment appear depressed during the systolic phase (gray waveform).

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  Fig. 4.. Morphological changes in ventricular surface and Na+/K+-ATPase expression after burn injury in bullfrog heart. Hematoxylin and eosin (H&E) (A) and Masson’s trichrome (B) staining in intact ventricular cardiomyocytes (Control) and those after the burn injury (Burned). Magnification ×20. (C) Immunohistochemistry using an antibody for Na+/K+-ATPase α-1 subunit (brown), counterstained with hematoxylin in intact ventricular cardiomyocytes (Control) and those after the burn injury (Burned). Magnification ×20.