Beta Blockers
What effect do beta blockers have on chronotropy (HR), inotropy (contractility), dromotropy (conduction velocity) and lusitropy (rate of relaxation of myocardium)?
Chronotropy: Decreased (lower HR)
Inotropy: Decreased (weaker contraction)
Dromotropy: Decreased (slower conduction)
Lusitropy: Decreased (slower relaxation)
i.e decreases all of them
What does ACE stand for?
Angiotensin Converting Enzyme
Converts Angiotensin I to Angiotensin II
What impact do diuretics have on blood pressure?
Decrease BP
(due to additional loss of fluid)
What class of cardiac drugs should not be paired with ACE Inhibitors?
Angiotensin Receptor Blockers (ARBs)
What adrenoreceptor type (e.g α1, β2, etc) is the main one in the heart?
β1
Beta blockers end with the suffix "-____"
"-olol" (e.g propranolol, esmolol, atenolol, etc)
Names of ACE Inhibitors end with the suffix "_____"
"-pril" (e.g benazepril, zofenopril, perindopril, and trandolapril)
What are the most and least potent classes of diuretics, respectively?
Loop diuretics and Potassium-sparing diuretics
ACE Inhibitor + Thiazide diuretic combo is used to treat
Heart failure or post-stroke
What adrenoreceptor type (e.g α1, β2, etc) is the main one in vascular smooth muscle cells?
α1
Beta blockers prevent _______ and _______ from binding to beta adrenergic receptors
Epinephrine and Norepinephrine (Adrenaline and Noradrenaline)
A persistent dry ____ is a common side effect of ACE inhibitors due to increased bradykinin
Cough.
Note: Patients who experience this side effect are often switched to ARBs
Loop diuretics, thiazide diuretics, and aldosterone antagonists have the suffixes "-____", "-____", and "-____", respectively
Loop: "-ide" (e.g furosemide)
Thiazide: "-thiazide" (e.g hydrochlorothiazide)
Aldosterone antagonists: "-actone" (e.g spironolactone)
ACE Inhibitor + beta blocker is used to treat
Post MI or patients with heart failure
Agonising β1 and β2 receptors in the SA node causes ____ to be released to increase the rate of spontaneous depolarisation and, therefore, the frequency of action potentials (increased chronotropy)
cAMP
Beta blockers are competitive antagonists at receptors which are [Gi/Gq/Gs] GPCRs
Gs
Which electrolyte should you be most worried about becoming elevated due to ACE inhibitors?
Potassium
ACE Inhibitors decrease aldosterone and, therefore, slow the secretion of Potassium. This can lead to hyperkalaemia.
Aldosterone stimulates the reabsorption of Sodium via Na/K transporters, which reabsorb 3 Na+ in exchange for secreting 2 K+.
Hence, by blocking aldosterone, we block the secretion of Potassium
Which type of diuretic (Loop, Thiazide, Aldosterone antagonists) would present a risk of hyperkalemia when combined with ACE inhibitors?
Aldosterone antagonists (aka one of the types of Potassium-sparing diuretics)
What sarcoplasmic reticulum receptor is activated by β1 agonism in cardiomyocytes?
SERCA2a
Beta blockers shouldn't be combined with _______ because of a risk of heart block
Verapamil (Calcium channel blocker)
Which organ should you be most concerned about when prescribing ACE inhibitors?
Kidneys
Renal dysfunction can occur due to a drop in renal perfusion pressure and, therefore, a decrease in GFR. This is due to ACE inhibitors' preferential vasodilation of the renal efferent arteriole, which impairs the kidneys' ability to compensate for low perfusion states
How do Loop diuretics work? (action, target, location of target)
Loop diuretics inhibit the Na-K-2Cl symporter in the thick ascending limb of the Loop of Henle
Which class of cardiac drugs would you combine with ACE inhibitors (or ARBs) when treating lipid abnormalities?
Calcium channel blocker
β2 receptor agonism causes vasodilation via vascular smooth muscle relaxation by what mechanism?
(will give full points if you get at least half of it right)
Adrenaline/Noradrenaline binding (agonism) → ↑ intracellular cAMP → inhibition of MLCK → ↓ MLC phosphorylation → dephosphorylated MLC does not bind actin → ↓ myosin-actin cross bridge formation → relaxation