Effect of glyceryl trinitrate (nitroglycerin) on the systemic and coronary circulation of the dog

The effect of glyceryl trinitrate (nitroglycerin) on systemic and coronary hemodynamics was studied in normal dogs by means of electromagnetic flowmeters and integrator computers. When given intravenously, glyceryl trinitrate produced changes in the hemodynamics which can be of benefit to the patient with angina pectoris. The drug first increased the coronary blood flow and cardiac index and reduced peripheral vascular resistance for about 20 seconds. This was followed by normal coronary flow with reduced peripheral and coronary vascular resistance, for about 60 seconds; at the same time cardiac work was markedly reduced. These results confirm that the beneficial effects of nitroglycerine are due to its action on the coronary as well as the systemic circulation.