RECEPTORS & AUTONOMIC FOUNDATIONS
These are the two major classes of cholinergic receptors activated by acetylcholine.
What are muscarinic and nicotinic receptors?
This prototypical sympathomimetic activates both alpha and beta receptors.
What is epinephrine?
This synthetic α1 agonist is commonly used to treat anesthesia-related hypotension and can cause reflex bradycardia.
What is phenylephrine?
PDE-3 inhibition increases intracellular levels of this second messenger.
What is cAMP?
This neurotransmitter activates cholinergic receptors in the parasympathetic nervous system.
What is acetylcholine?
TWO PARTS:
1. This adrenergic receptor causes vasoconstriction, increases peripheral resistance and BP, produces mydriasis, and contracts the bladder sphincter.
2. This adrenergic receptor inhibits norepinephrine release, acetylcholine release, and insulin release.
1. What is α1?
2. What is α2?
This catecholamine acts primarily at α1 with some β1 activity and can cause profound vasoconstriction with reflex bradycardia.
What is norepinephrine?
This mixed-acting sympathomimetic directly stimulates β1/β2 receptors and indirectly causes norepinephrine release.
What is ephedrine?
Increased cAMP activates protein kinase A, increasing this ion in cardiac myocytes and thereby increasing contractility.
What is calcium/Ca²⁺?
- This prototype antimuscarinic increases HR, decreases secretions, causes mydriasis, and decreases GI motility.
- Bradycardia, heart block, antisialagogue use, and organophosphate poisoning are clinical uses of this drug.
- Tachycardia, urinary retention, constipation, and prolonged dilated pupils are adverse effects of this antimuscarinic.
- Dilates the pupil by blocking muscarinic receptors on the iris sphincter muscle, removing parasympathetic constrictor tone and allowing unopposed dilation.
What is atropine?
TWO PARTS:
1. Stimulation of this receptor increases heart rate, myocardial contractility, conduction, and renin release.
2. Bronchodilation, vascular smooth-muscle relaxation, and uterine relaxation are major effects of this receptor.
1. What is β1?
2. What is β2?
This synthetic beta-1 agonist is primarily inotropic, increases contractility, and has relatively little chronotropic effect. Usually decreases SVR. Used for heart failure and cardiogenic shock.
What is dobutamine?
This drug has no direct inotropic or chronotropic effect but is a potent vasoconstrictor. Produces potent vasoconstriction through alpha-1 adrenergic receptor. Also known as ADH. Drug of choice for hypotension during adrenalectomy.
What is vasopressin?
TWO PARTS:
1. Hypotension, dysrhythmias, thrombocytopenia, hypokalemia, and angina are adverse effects associated with this drug class.
2. A drug in (part 1's class) is commonly described as an “inodilator” because it increases contractility while producing vasodilation. In vascular smooth muscle, this drug's cAMP elevation reduces calcium influx, causing relaxation and vasodilation — the mechanism behind its reduction of systemic and pulmonary vascular resistance.
1. What are PDE-3 inhibitors?
2. What is milrinone?
This antimuscarinic does not cross the blood-brain barrier and is frequently paired with neostigmine.
What is glycopyrrolate?
THREE PARTS:
1. In pharmacology, this term describes a drug that activates a receptor and produces its effect.
2. This term describes a drug that binds to a receptor and blocks its effect.
3. Unlike a full agonist, this type of drug produces less than 100% of the maximal receptor effect.
1. What is an agonist?
2. What is an antagonist?
3. What is a partial agonist?
This β1 and β2 agonist has no significant alpha activity and may increase cardiac output while decreasing MAP.
Hint: Undergoes rapid liver metabolism by COMT, meaning a continuous infusion is required to sustain its beta-agonist effect rather than a single dose.
What is isoproterenol?
TWO PARTS
1. Typical IV bolus dose of phenylephrine given in the lecture is this range.
2. The lecture gives this typical IV bolus dose range for ephedrine.
1. What is 50–100 mcg IV?
2. What is 5–10 mg IV?
Calcium chloride is more concentrated (_____ mg/ml) than calcium Gluconate (_____ mg/ml)
Calcium chloride is more concentrated (27mg/ml) than Calcium Gluconate (9mg/ml).
Glycopyrrolate reversal: ___ mg for every 1mg of neostigmine
0.2 mg
Name the three cardiac properties represented by increased heart rate, increased contractility, and increased conduction velocity.
What are chronotropy, inotropy, and dromotropy?
Direct-acting catecholamine primarily used for shock. Onset/peak/duration and renal blood flow changes at high doses. (Hint: strongly dose dependent)
What is dopamine?
A patient receives repeated ephedrine boluses, but each dose becomes less effective. Explain the mechanism of this declining response and name the pharmacologic phenomenon.
What is depletion of norepinephrine stores causing tachyphylaxis?
TWO PARTS:
1. This drug is used primarily for methemoglobinemia but may also be used in refractory vasoplegia or hypotension.
2. Part 1's answer raises blood pressure by blocking the nitric oxide synthase and _____ pathway, removing a key vasodilatory signal and promoting vasoconstriction.
1. What is methylene blue?
2. What is soluble guanylate cyclase?
This selective α2 antagonist increases norepinephrine levels, has been used for orthostatic hypotension and erectile dysfunction, and has largely been replaced by PDE-5 inhibitors. Bonus: Name a phosphodiesterase-5 inhibitors
1. What is yohimbine?
2. What is sildenafil?