The Correct Answer is C!


A 66-year-old man presents to the emergency department with three hours of chest pain. He is given sublingual nitroglycerin, and his BP falls to 60 mmHg with near syncope. He now admits to having taken sildenafil an hour before the onset of chest pain.

What is the mechanism of his hypotension?

A. Increased levels of prostaglandin (PG12)
B. Decreased production of thromboxane synthase
C. Excess cGMP-mediated vasodilation
D. Endothelial-independent vasodilation


Nitrates taken with PDE5 inhibitors produce excess cGMP-mediated vasodilation due to an increase in nitric oxide, which enhances the guanylate-cyclase conversion of GTP to cGMP.

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