This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
The mechanism of action of Sodium nitroprusside is 
Select and explain. 
A. Increased cAMP, B. Stimulation of guanylate cyclase, C. Calcium channel blockers, D. Potassium channel blocker
B: Stimulation of guanylate cyclase
Answer: B: Stimulation of guanylate cyclase 
Explanation: Sodium nitroprusside acts by releasing nitric oxide(NO). This stimulate guanylate cyclase and results in the elevation of cGMP, which are vasodilators. Refer kDT 6/e p549