All are true about nitric oxide, EXCEPT:
(A) Regulates vasomotor tone (B) Acts via cAMP (C) Present in cigarette smoke (D) It is important in penile erection
(B) Nitric oxide is a potent vasodilator and serves to regulate vascular tone. Produced in the endothelium it freely diffuses to the nearby smooth muscle cell and activates a soluble guanylyl cyclase (sGC) raising cytosolic cGMP concentration. This in turn activates a cGMP-dependent protein kinase (PKG).