Question
NO acts on platelets through:
| A. | cAMP |
| B. |
Adenosine |
| C. |
cGMP |
| D. |
TX-A2 |
|
Correct Answer � C Explanation |
 |
Ans. is ‘c’ i.e., cGMP
Nitric oxide (NO) is a neurotransmitter in the CNS.
It is also the important neurotransmitter in the neuromuscular junctions between the inhibitory motor fibers of the intrinsic nerve plexus and the smooth muscle fibers of the GI tract.
Nitric oxide acts as a mediator for the dilator effect of Ach on small arteries. In the smooth muscle fibers of arterioles, NO activates the enzyme guanylyl cyclase, which in turn causes the formation of cyclic guanosine monophosphate (cGMP) from GMP. The cGMP is a smooth muscle relaxant and it causes dilatation of arterioles. Thus, NO indirectly causes dilatation of arterioles.
The peculiarity of NO is that it is neither produced by the neuronal cells nor stored in the vesicles. It is produced by nonneuronal cells like the endothelial cells of blood vessels.
From the site of production, it diffuses into the neuronal and non-neuronal cells where it exerts its action.