What effect does Glyceryl Trinitrate have on the blood vessels?

Glyceryl Trinitrate, commonly known as GTN or nitroglycerin, is a medication primarily used as a vasodilator. Its primary mechanism of action involves relaxation of the smooth muscle in the walls of blood vessels, leading to dilation, especially in venous and arterial circulation. This dilation reduces the return of blood to the heart (preload) and decreases the workload on the heart by lowering systemic vascular resistance (afterload).

The dilation of blood vessels by GTN serves important therapeutic purposes, particularly in the management of conditions such as angina pectoris and acute heart failure. By decreasing myocardial oxygen demand and improving blood flow through the coronary arteries, it helps alleviate symptoms associated with ischemia and enhances overall cardiac function during periods of stress.

In context with other choices, blood vessel constriction would counteract the therapeutic effects of GTN, and a medication that thickens blood or lowers blood viscosity does not reflect the pharmacological properties of glyceryl trinitrate, which is all about dilation and relaxation of the vascular smooth muscle.