Basic Science Concepts Flashcards
Muscarinic receptors
- Endogenous substrate: ACh
- Agonist action: ↑ SLUDD
- Drug agonists: pilocarpine, bethanechol
- Antagonist action: ↓ SLUDD
- Drug antagonists: atropine, oxybutynin
Nicotinic receptors
- Endogenous substrate: ACh
- Agonist action: ↑ HR, BP
- Drug agonists: nicotine
- Antagonist action: neuromuscular blockade
- Drug antagonists: neuromuscular blockers (e.g., rocuronium)
Alpha-1 receptors
Mainly peripheral
- Endogenous substrate: Epi, NE
- Agonist action: smooth muscle vasoconstriction, ↑ BP
- Drug agonists: phenylephrine, dopamine (dose-dependent)
- Antagonist action: smooth muscle vasodilation, ↓ BP
- Drug antagonists: alpha-1 blockers (e.g., doxazosin, carvedilol, phentolamine)
Alpha-2 receptors
Mainly brain; central
- Endogenous substrate: Epi, NE
- Agonist action: ↓ release of Epi & NE, ↓ BP, HR
- Drug agonists: clonidine, brimonidine (ophthalmic, for glaucoma)
- Antagonist action: ↑ BP, HR
- Drug antagonists: ergot alkaloids, yohimbine
Beta-1 receptors
Mainly heart
- Endogenous substrate: Epi, NE
- Agonist action: ↑ myocardial contractility, CO, HR
- Drug agonists: dobutamine, isoproterenol, dopamine (dose-dependent)
- Antagonist action: ↓ CO, HR
- Drug antagonists: beta-1 selective blockers (e.g., metoprolol) and non-selective beta-blockers (e.g., propranolol, carvedilol)
Beta-2 receptors
Mainly lungs
- Endogenous substrate: Epi
- Agonist action: bronchodilation
- Drug agonists: albuterol, terbutaline, isoproterenol
- Antagonist action: bronchoconstriction
- Drug antagonists: non-selective beta-blockers (e.g., propranolol, carvedilol)
Dopamine receptors
- Endogenous substrate: DA
- Agonist action: many, including renal, cardiac and CNS effects
- Drug agonists: levodopa, pramipexole
- Antagonist action: many, including renal, cardiac and CNS effects
- Drug antagonists: FGAs (e.g., haloperidol), metoclopramide
Serotonin receptors
- Endogenous substrate: 5-HT
- Agonist action: many, including platelet, GI and psychiatric effects
- Drug agonists: triptans (e.g., sumatriptan)
- Antagonist action: many, including platelet, GI and psychiatric effects
- Drug antagonists: ondansetron, SGAs (e.g., quetiapine)
Acetylcholinesterase
Breaks down acetylcholine
Angiotensin-converting enzyme (ACE)
Coverts angiotensin I to angiotensin II (a potent vasoconstrictor)
Catechol-O-methyltransferase (COMT)
Breaks down levodopa
Cyclooxygenase
Converts arachidonic acid to prostaglandins (cause inflammation) and thromboxane A2 (causes platelet aggregation)
Monoamine oxidase (MAO)
Breaks down catecholamines (e.g., DA, NE, Epi, 5-HT)
Phosphodiesterase (PDE)
Breaks down cyclic guanosine monophosphate (cGMP), a smooth muscle relaxant
Vitamin K epoxide reductase
Converts vitamin K to the active form required for production of select clotting factors
