Lecture 23: Drug development - Beta blockers and Statins Flashcards
Where are alpha 1 receptors found?
Vascular smooth muscle
What is the mechanism of action of alpha 1 receptors?
Gq protein coupled activates phospholipase C, IP3 and DAG
What are the physiological effects of alpha 1 receptors?
- Smooth muscle contractions
- Gluconeogenesis
- Vasocnstriction
What are the alpha 1 receptor agonists?
- Norepinephrine
- Phenylephrine
- Methoxamine
What are the alpha 1 receptor antagonists?
- Doxazosin
- Phentolamine
- Prazosin
Where are alpha 2 receptors found?
- Pre synaptic terminals
- Pancreas
- Platelets
- Ciliary epithelium
- Salivary glands
What is the mechanism of action of alpha 2 receptors?
Gi protein coupled inhibits adenyl cyclase
What is the mechanism of action of alpha 2 receptors?
Gi protein coupled inhibits adenyl cyclase
What are the physiological effects of alpha 2 receptors?
Inhibits release of neurotransmitters
What are the alpha 2 receptor agonists?
- Clonidine
- Monoxidine
What are the alpha 2 receptor antagonists?
- Yohombine
- Idazoxan
- Tolazoline
Where are beta 1 receptors found?
- Heart
- Kidney
- Some presynamptic terminals
What is the mechanism of action of beta 1 receptors?
Gs protein coupled activates adenyl cyclase + PKA
What are the physiological effects of beta 1 receptors?
Increase heart rate and renin secretion
What are beta 1 receptor agonists?
- Isoproternol
- Norepinephrine
- Dobutamine
What are beta 1 receptor antagonists?
- Propanolol
- Metoprolol
- Atenolol
Where are beta 2 receptors found?
- Visceral smooth muscles
- Bronchioles
- Liver
- Skeletal muscles
What is the mechanism of action of beta 2 receptors?
Gs protein coupled activates adenyl cyclase and PKA, Ca channels
What are the physiological effects of beta 2 receptors?
- Vasodilation
- Bronchodilation
- Inhibits insulin secretion
What are beta 2 receptor agonists?
- Isoproterenol
- Salbutamol
- Salmeterol
- Albuterol
- Formoterol
- Terbutaline
- Levalbuterol
What are the beta 2 receptor antagonists?
- Propanolol
- ICI 118,551
- Nadolol
- Butoxamine
What are beta blockers used to treat?
- Angina
- Heart failure
- Atrial fibrilation
- Hypertension
What do beta blockers do?
Slow the SA node which initiates a heartbeat. The slow heart rate allows the left ventricle to fill completely and lowers the heart workload.
What do beta 1 receptors acting on the kidney do?
Renin relaese
What do beta 1 receptors acting on the adipose tissue do?
Lipolysis
What do beta 1 receptors acting on the heart affect?
- Rate
- Force
- Automaticity
- Cardiac output
What are the effects of beta blockers on the heart?
- Decreased heart rate
- Decreased contractility
- Decreased conduction
What are the effects of beta blockers on the kidney?
- Decreased renin release from renal juxtaglomerular cells
What are the cardiovascular beneficial effects of beta blockers?
- Decreased blood pressure
- Decreased myocardial oxygen demand
- Decreased water and salt retention
- Decreased oxidative and inflammatory stress
- Attenuated cardiovascular remodeling
What are beta adrenoreceptors?
G protein coupled receptors which activate adenylyl cyclase to form cAMP from ATP when stimulated by noradrenaline
What causes calcium entry into a cell?
Increased cAMP activated a cAMP dependant protein kinase (PK-A) that phosphorylates L type calcium channels, which cause increased calcium entry into the cell
What does in increase of calcium entry lead to?
Leads to enhanced release of calcium by the sarcoplastic reticulum in the heart, these actions increase inotropy (contractility)
What are the actions of PK-A?
- Phosphylate myosin light chain
- Phosphorylate L type calcium channels
What does phosphorylation of L type calcium channels result in?
Increased calcium entry into the cell