Experimental studies on the effect of glucocorticoids on cardiac muscle.

Abnormal electrocardiographic changes were found in some patients on long-term glucocorticoid treatment. In experimental animals, chronic glucocorticoid administration resulted in an increase of amplitude of the QRS complex and abnormal ST and T changes. Changes of action potential were somewhat different in the subendocardial and the subepicardial layers. Diffuse mitochondrial alterations were found, particularly in the subepicardial layer. In rabbits treated with glucocorticoids, no significant changes were found in either serum or myocardial potassium content. Slightly decreased Vmax was the observed hemodynamic change.