Australian Dental Council (ADC) Practice Test

Glycerine trinitrate, also known as nitroglycerin, primarily works in patients with angina by causing venous dilation, which leads to a decrease in venous return. This reduction in venous return lowers the amount of blood returning to the heart, subsequently reducing the preload – the volume of blood in the ventricles at the end of diastole. With a decreased preload, the heart doesn't have to work as hard, lowering its oxygen demand.

This mechanism is particularly beneficial for patients with angina, whose heart muscle is already compromised due to insufficient blood supply. By alleviating the workload on the heart, glycerine trinitrate effectively helps to relieve the pain associated with angina attacks. The other options do not accurately reflect the primary mechanism of action of glycerine trinitrate, making the selected answer more appropriate in the context of angina treatment.