Inotropes and cardiovascular receptors Flashcards
1
Q
Inotropes are a class of drugs which work primarily by increasing cardiac output.
A
They should be distinguished from vasoconstrictor drugs which are used specifically when the primary problem is peripheral vasodilatation.
2
Q
Catecholamine type agents?
A
- work by increasing cAMP levels by adenylate cyclase stimulation.
- This in turn intracellular calcium ion mobilisation and thus the force of contraction.
3
Q
Adrenaline?
A
- works as a beta adrenergic receptor agonist at lower doses
- and an alpha receptor agonist at higher doses.
- Dopamine causes dopamine receptor mediated renal and mesenteric vascular dilatation and beta 1 receptor agonism at higher doses.
- This results in increased cardiac output.
4
Q
Since both heart rate and blood pressure are raised?
A
- there is less overall myocardial ischaemia.
- Dobutamine is a predominantly beta 1 receptor agonist with weak beta 2 and alpha receptor agonist properties
5
Q
Noradrenaline?
A
- is a catecholamine type agent and
- predominantly acts as an alpha receptor agonist and
- serves as a peripheral vasoconstrictor.
6
Q
Phosphodiesterase inhibitors such as milrinone ?
A
- act specifically on the cardiac phosphodiesterase and
- increase cardiac output.
7
Q
Inotrope - Adrenaline?
A
- α-1, α-2, β-1, β-2
8
Q
Inotrope - Noradrenaline
A
- α-1,( α-2), (β-1), (β-2)
9
Q
Inotrope - Dobutamine?
A
- β-1, (β 2)
10
Q
Inotrope - Dopamine?
A
- (α-1), (α-2), (β-1), D-1,D-2
11
Q
Effects of receptor binding - α-1, α-2?
A
- vasoconstriction
12
Q
Effects of receptor binding - β-1?
A
- increased cardiac contractility and HR
13
Q
Effects of receptor binding - β-2?
A
- vasodilatation
14
Q
Effects of receptor binding - D-1/D-2?
A
- D-1 renal and spleen vasodilatation
- D-2 inhibits release of noradrenaline
