Renin-Angiotensin-Aldosterone

From Ganfyd

Angiotensin I as molecular model

Steps involved in RAA

The renin-angiotensin system

1. Renin is produced and released from the juxtaglomerular apparatus due to renal hypoperfusion.
   • Its production is blocked by betablockers.
2. Renin converts Angiotensinogen to Angiotensin I
   • Renin inhibitors such as aliskiren work at this step
   • Cathepsin D and Tonins can also catalyse conversion
3. In the lungs the endothelium contains angiotensin converting enzyme* which converts Angiotensin I to Angiotensin II a potent vasoconstrictor
   • ACE inhibitors work at this step

Angiotensin II as molecular model

1. Angiotensin II stimulates Aldosterone release from the adrenal cortex
   • Angiotensin receptor blockers work at this step (on the AT₁-R receptor protein)
2. Aldosterone causes salt and water retention.

See also Remodelling and a historical footnote in ACE inhibitors

Note that there are four known AT receptor proteins (see Angiotensin):

1. AT₁-R - stimulatory
2. AT₂-R - inhibitory
3. AT_1-7-R - inhibitory (mas receptor)
4. AT₄-R - multiple neuroendocrine actions

Blocked classically by ACE inhibitors and angiotensin II blockers

Angiotensin I chemical structure

Angiotensin II chemical structure (note: - the raw data for both from KEGG)