Review Question - QID 212622

A 52-year-old man presents to his primary care physician for an annual check-up. He says that he has no significant developments over the last year and that he has been feeling well in general. On presentation, his temperature is 98.6°F (37°C), blood pressure is 140/95 mmHg, pulse is 85/min, and respirations are 12/min. This is the third time that he has had elevated blood pressure so his physician suggests that he start taking a medication for hypertension. The patient is a biologist so he researches this medication after returning home. He finds that the medication can either decrease or increase the level of cyclic adenosine monophosphate depending on whether there is endogenous substrate around. Which of the following medications is mostly likely being described here?