Targets and the Renin-Angiotensin-Aldosterone System Flashcards
How does the RAAS system control blood pressure?
- Altering vascular tone
2. Controlling natriuresis
Describe the process from renin to angiotensin II
Renin produced by juxtaglomerular cells
Renin catalyses conversion of angiotensinogen into angiotensin I
ACE from endothelial cells converts angiotensin I into angiotensin II
Which receptor does angiotensin II act through?
AT-1
What happens beyond angiotensin II?
It can be further cleaved into angiotensin III and angiotensin IV. Ang III promotes aldosterone secretion. Ang IV inhibits clot clearance
Where does aldosterone bind to and what is its mechanism?
Binds aldosterone receptors in collecting tubule
Increases apical Na+ channels and basolateral Na/K transporters
What are the drugs targeting RAAS?
ACE inhibitors
Angiotensin receptor antagonists
Beta blockers
Diuretics
What is an example of an ACE inhibitor?
Cilazipril
What is another effect of ACE?
Increases bradykinin which causes side effects: dry cough and angioedema
What is angioedema?
Abnormal swelling in the lips, larynx or pharynx
Very low frequency but can be avoided by bradykinin specific treatment
How do angiotensin receptor blockers (ARB) work?
Antagonist of AT-1 receptor and blocks most RAAS activity (losartan)
Which is more effective out of ARB and ACE-1?
ACE-1
Don’t use them together
How do aldosterone antagonists (spirinolactone) work?
Antagonist at mineralocorticoid receptor, inhibits Na+ reabsorption by aldosterone
What do calcium channel blockers do?
Inhibit smooth muscle contraction so decrease blood pressure
What is the method of action of diuretics?
Loop diuretics (thiazide and amiloride) reduce sodium reabsorption. Osmotic diuretics increase osmolarity of filtrate
What is the action of beta blockers?
Mainly acts on SNS as competitive antagonist to B1 receptor
Decrease cardiac contractility and decrease renin secretion
