On the mode of action of antianginal drugs.

The antianginal action of coronary dilating drugs seems to be related at least partly to their effect of improving the blood supply of the ischemic myocardium. No correlation was found between coronary dilating action of these drugs in the normal myocardium and in the ischemic area, however. It has been shown that coronary dilator drugs are able to produce a further dilatation of the vascular bed which is already in maximum hypoxic dilatation. The antianginal effect of adrenergic beta receptor blockade cannot be explained solely by its negative chronotropic and inotropic action. It involves a favourable redistribution of the coronary flow which is increased in the ischemic area. In addition, there is evidence for a direct cardiac metabolic effect of beta blockade which reduces the myocardial oxygen requirement and moderates the ischemic diminution of the myocardial lactate uptake independently of its action on the autonomic nervous control and other extracardiac factors as well as on contractility, heart rate and myocardial blood supply.