Indicate true (T) and false (F) statements below regarding cellular signaling mediated by nitric oxide (NO). Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF.
( ) Once produced, NO can diffuse to neighboring cells.
( ) NO has known roles in cGMP-independent as well as cGMP-dependent signaling.
( ) NO normally decreases cGMP concentration by activating cGMP phosphodiesterase.
( ) The drug Viagra® counteracts the effects of NO on penile blood vessels.

Question

Indicate true (T) and false (F) statements below regarding cellular signaling mediated by nitric oxide (NO). Your answer would be a four-letter string composed of letters T and F only, e.g. TTTF.
( )	Once produced, NO can diffuse to neighboring cells.
( )	NO has known roles in cGMP-independent as well as cGMP-dependent signaling.
( )	NO normally decreases cGMP concentration by activating cGMP phosphodiesterase.
( )	The drug Viagra® counteracts the effects of NO on penile blood vessels.

Quizplus · Accepted Answer

Dissolved NO passes readily across cell membranes and can diffuse from its site of production to neighboring smooth muscle cells, where it increases cyclic GMP concentration by activating guanylyl cyclase. The drug Viagra® and its relatives inhibit cyclic GMP phosphodiesterase in the penis, allowing the effects of NO to last longer. NO can also signal cells independently of cyclic GMP.

Indicate True (T) and False (F) Statements Below Regarding Cellular