The effects of acetylstrophanthidin and glucocorticoids on canine left ventricular performance and coronary hemodynamics.

The effects of acetylstrophanthidin and methylprednisolone, individually and in combination, on coronary vascular resistance and left ventricular function were determined in an isolated dog heart preparation. The preparation permitted control of peak left ventricular pressure (and systolic tension) independent of inotropic actions by the drug and, thus, allowed direct measurements of its effect on coronary vascular resistance. The digitalis preparation initially increased coronary vascular tone and increased left ventricular performance; the increase in performance was followed by a decrease in coronary vascular resistance ascribed to metabolic effects. This response pattern was essentially unaltered when methylprednisolone was administered one hour before digitalis. Methylprednisolone itself depressed myocardial performance in this preparation, with a decrease in coronary vascular resistance after 30 minutes. Both agents also had a negative chronotropic action.