Steps involved in RAA
- Renin is produced and released from the juxtaglomerular apparatus due to renal hypoperfusion.
- Its production is blocked by betablockers.
- Renin converts Angiotensinogen to Angiotensin I
- 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 stimulates Aldosterone release from the adrenal cortex
- Angiotensin receptor blockers work at this step (on the AT1-R receptor protein)
- Aldosterone causes salt and water retention.
Note that there are four known AT receptor proteins (see Angiotensin):
- AT1-R - stimulatory
- AT2-R - inhibitory
- AT1-7-R - inhibitory (mas receptor)
- AT4-R - multiple neuroendocrine actions