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NO/guanylate cyclase/cGMP pathway

Created: 19/7/2006
Updated: 21/5/2006

 

NO/guanylate cyclase/cGMP pathway

A schematic representation of the NO/guanylate cyclase/cGMP pathway is shown below. With appropriate stimulation NO is released from NANC fibres and penile vascular endothelium in response to cholinergic innervation. NO diffuses freely into cavernosal smooth muscle where it activates soluble guanylate cyclase (sGC). sGC converts GTP to cGMP. Intracellular cGMP levels are controlled by the phosphodiesterase type-5 enzyme (PDE-5), which hydrolyses it to its inactive form, 5’GMP. cGMP accumulation results in the activation of a specific protein kinase G. This causes potassium channels to open, hyperpolarisation of the cell membrane, sequestration of intracellular calcium by the endoplasmic reticulum, and blocking of calcium influx via the inhibition of calcium channels. The result is a drop in cytosolic calcium levels and relaxation of smooth muscle.





ArticleDate:20060719
SiteSection: Article
 
   
    
                                            



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