Question 417: Up up and away

THis describes the mechanism of what has been deemed as a miracle for mankind.

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The mechanism of action of___X___ involves the protection of cyclic guanosine monophosphate (cGMP) from degradation by cGMP-specific phosphodiesterase type 5 (PDE5) in the corpus cavernosum. Nitric oxide (NO) in the corpus cavernosum of the _____ binds to guanylate cyclase receptors, which results in increased levels of cGMP, leading to smooth muscle relaxation (vasodilation) of the intimal cushions of the helicine arteries. This smooth muscle relaxation leads to vasodilation and increased inflow of blood into the spongy tissue, causing ________ . Robert F. Furchgott won the Nobel Prize in Physiology or Medicine in 1998 for his discovery and analysis of endothelium-derived relaxing factor or "EDRF", later identified with NO itself or a closely-related compound.