Fig. 1. NO-dependent signaling pathways in cardiac myocytes. After binding acetylcholine,
the m2 muscarinic cholinergic receptor (m2 AChR) is translocated into caveolae where
among other signal transduction events eNOS is activated and NO is produced. The
principal downstream target for NO and for nitrovasodilators (such as nitroglycerin) is
guanylyl cyclase (GC). The net effect of the subsequent increase in intracellular cGMP on a
specific cellular target, the Ica_ L in the example here, will depend on the extent of activation …