A 61-year-old man with erectile dysfunction asks his physician to prescribe Viagra® (sildenafil citrate; Pfizer Inc., Mission, KS, USA). Sildenafil produces its physiological effects by blocking the enzyme that hydrolyzes the second messenger by which nitric oxide produces its physiological effects. Which of the following is the second messenger?  
a. Cyclic guanosine monophosphate (cGMP)  
b. cGMP phosphodiesterase (PDE)  
c. Diacylglycerol  
d. G protein  
e. Guanylate cyclase

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Aus CGMP Cyclic guanosine mono phosphate is ... View the full answer