What is the important action of nitrates in angina?

Ans. B. Decreases preloadNitrates cause release of nitric oxide which causes activation of guanylyl cyclase and through series of steps (via activation of protein kinase and phosphatases) activate myosin light chain through dephosphorylation which causes smooth muscle relaxation and hence vasodilatation. This decreases systemic vascular resistance and there will be increased pooling of blood. All of these events can lead to decrease in preload.