The Effects of Nitroglycerin and Amyl Nitrite

coronary arteries, -4 or that they diminish the oxygen requirements of the myocardium by diminishing the external work of the heart.5'6 Much of the confusion concerning the actions of these drugs has arisen from the assumption that nitroglycerin and amyl nitrite have similar effects. Moreover, many studies on the peripheral circulatory effects of nitrites have been carried out with sodium nitrite, administered orally or intravenously, and it has generally been considered that the actions of this substance resemble those of nitroglycerin and of amyl nitrite. In order to determine whether the peripheral circulatory actions of nitroglycerin and amyl nitrite might play a role in their therapeutic effects, the actions of these drugs on both the resistance and capacitance vessels of the forearm of normal human subjects were determined, and the results of these studies are described in this report. The effects of nitroglycerin on ventricular dimensions are described elsewhere.7 The results of these two investigations suggest the manner in which the actions of these drugs on the peripheral circulation affect the heart, and they afford additional insight into the mechanism by which nitroglycerin and amyl nitrite provide relief of anginal pain.