RAAS Flashcards
RAAS
Angiotensin II and aldosterone regulate fluid and BP
Renin
Produced in the kidney, release can be triggered by multiple factors:
Decrease in BP
Decrease in blood volume
Decrease in plasma sodium content
Decrease in renal perfusion
Renin causes formation of angiotensin I from angiotensin (secreted by liver)
Angiotensin system
Angiotensin I (inactive) has weak activity in the body, and precursor to II Kinase II (found in blood) converts angiotensin I to II
Angiotensin II
Vasoconstriction (more effect on arteries)
Stops nitric oxide to stop vasodilation
Stimulation of aldosterone
Angiotensin II indirect actions
Sympathetic neurons to promote NE release
Adrenal medulla to promote Epi release
On adrenal cortex to promote secretion of aldosterone
Aldosterone
Aldosterone acts on distal tubules in the kidney to cause sodium retention, and excretion of K+ and H+
4 main drug families affect RAAS
ACE inhibitors
ARBs (angiotensin II receptor blockers)
Direct renin inhibitors (DRIs)
Aldosterone antagonists
ACE inhibitors
Stop conversion of angiotensin I to II
Adverse effects include cough, angioedema, first dose hypotension, and hyperkalemia
More ACE inhibitors sides
10% get dry, persistent cough
Stopping can cause potassium retention in kidney
HyperK+ rare, but pts shouldn’t be taking K+ supp
ACE inhibitor MAO
Reduce level of angiotensin II
Increase levels of bradykinin (inhibits kinase II)
End result is non constricted blood vessels and stop release of aldosterone
Ace inhibitor name
Pril Benazepril Captopril Enalapril Lisinopril Ramipril
ARBs
Block actions of angiotensin II
Lower risk of cough and hyperk+
Usually secondary to ace inhibitors which have better success in decreased cardiac morbidity and mortality
ARBs
Block angiotensin II, also block release of aldosterone and so Na+ and H2O excretion is increased
ARBs names
Sartan Losartan Valsartan Olmesartan Eprosartan Candesartan
DRIs
Direct Renin inhibitors
Act on renin to inhibit conversion of angiotensin to angiotensin I
Aliskiren is the only one, used for HTN
Aldosterone antagonists
Block receptors for aldosterone for HTN and heart failure
2 drugs - eplerenone and spironolactone - K+ sparing diuretic
Aldosterone receptors
In the kidney, activation of aldosterone receptors promotes excretion of K and retention of Na+ and H2O
Receptor blockade has opposite effect, retention of K+ and excretion of Na+ and H2O
ACE inhibitors used in
HTN, CHF, diabetic neuropathy, MI and prevention of cardiovascular risks
ARBS indications
HTN, CHF, diabetic neuropathy