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103 Cards in this Set
- Front
- Back
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Neurotransmitter of preganglionic neurons
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Acetylcholine
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Neurotransmitters of postganglionic neurons
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Acetylcholine, norepinephrine, epinephrine, dopamine
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Mechanism of miosis
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Sphincter muscle of the pupilla has M3 receptors. Muscarinic agonists causes contraction and miosis. Muscarinic antagonists cause relaxation and mydriasis with cycloplegia.
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Mechanism of mydriasis
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Dilator muscle of the pupilla has α1 receptors. α1 agonists cause contraction and mydriasis without cycloplegia. Also muscarinic blockers.
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Mechanism of accomodation
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Ciliary muscle has M3 receptors. Muscarinic agonists cause contraction and widening of the lens for close vision. Muscarinic antagonists cause cycloplegia and stretching of the lens for far vision.
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Muscarinic receptors of the eye
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Sphincter of the pupilla and cilliary muscles --> M3 --> miosis and accomodation
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Muscarinic receptors of the heart
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SA node and AV node --> M2 --> decrease heart rate, decrease conduction velocity
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Muscarinic receptors of the lungs
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Bronchioles and glands --> M3 --> bronchospasm and gland secretion
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Muscarinic receptors in the GI tract
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Stomach, intestines --> M3 --> increased motility, cramps, diarrhea; GI glands --> M1 --> gland secretion
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Muscarinic receptors of the bladder
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M3 --> contraction of detrusor, relaxation of the trigone/sphincter --> urination and urinary incontinence
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Muscarinic receptors of sphincters (GI, GU)
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M3 --> relaxation, excep LES which contracts
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Muscarinic receptors of glands
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M3 --> gland secretion --> sweat, salivation, lacrimation
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Muscarinic receptors in endothelium
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M3 --> cause vasodilation via release of NO
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Location of M3 receptros
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Eye (sphincter and cilliary), smooth muscle of bronchioles, GU and GI, glands except GI, sphicters, endothelium.
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Net effects of M3 receptor activation
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Miosis, accomodation, salivation, lacrimation, sweating, bronchoconstriction, increased GI motility, relaxation of sphincters (except LES), release of NO (indirect vasodilation).
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Net effects of M2 receptor activation
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Decreased heart rate, decreased conduction velocity of AV node.
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Net effects of M1 receptor activation
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Gland secretions of the GI tract.
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Receptors in the adrenal medulla
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Nn --> secretion of epinephrine and norepinephrine
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Receptors at the neuromuscular junction
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Nm --> muscle depolarization and contraction
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Receptors in autonomic ganglia
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Nn --> net effects depend on PANS/SANS dominance
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Muscarinic receptor mechanisms and second messenger systems
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M1, M3 --> Gq; M2 --> Gi; Nn, Nm --> Na/K channels
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Hemicholinium
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Inhibits reuptake of choline decreasing Ach synthesis (anticholinergic)
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Botulinum toxin
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Blocks release of ACh. Used in blepharospasm, strabismus, dystonia, cosmetics.
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Direct muscarinic agonists
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ACh, bethanecol, methacholine, pilocarpine
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Properties and use of acethylcholine
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Acts on muscarinic and nicotinic receptors. Strongly hydrolised by AChE. No clinical use.
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Properties and use of bethanecol
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Acts on muscarinic receptors. No AChE hydrolisis. Rx.: paralytic ileus, urinary retention
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Properties and use of methacholine
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More muscarinic than nicotinic actions. Weakly hydrolised by AChE. Used to Dx. Bronchial hyperreactivity.
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Properties and use of pilocarpine
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Acts on muscarinic receptors. Not hydrolyzed by AChE. Used for Rx. of glaucoma and xerostomia.
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Rx. of paralytic ileus
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Bethanecol, neostigmine, pyridostigmine
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Rx. of urinary retention
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Bethanecol, neostigmine, pyridostigmine
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Dx of bronchial hyperreactivity
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Methacholine
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Rx of glaucoma and xerostomia
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Pilocarpine, physostigmine
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Acetylcholinesterase inhibitors
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Edrophonium, physostigmine, neostigmine, pyridostigmine, donepezil, tacrine, organophosphates (irreversible)
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Properties and use of edrophonium
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Short acting AChE inhibitor. Dx myasthenia gravis
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Properties and use of physostigmine
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Tertiary amine AChE inhibitor. Rx glaucoma, antidote in atropine overdose
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Properties and use of neostigmine and pyridostigmine
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Cuaternary amines AChE inhibitors. Rx paralytic ileus, urinary retention, myasthenia, reversal of nondepolarizing NM blockers
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Properties and use of donepezil and tacrine
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Lipid-soluble AChE inhibitor enters CNS. Rx Alzheimer disease.
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Properties and use of organophosphates
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Lipid soluble irreversible AChE inhibitors. Rx glaucoma. Also insecticides parathion, malathion and nerve gas sarin.
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Dx and Rx of myasthenia gravis
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Edrophonium (Dx), neostigmine, pyridostigmine (Rx)
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Rx Alzheimer disease
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Donepezil, tacrine
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Signs and symptoms of organophosphate intoxication
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"Dumbbelss" Diarrhea, urination, miosis, bradycardia, bronchoconstriction, excitation, lacrimation, salivation, sweating.
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Rx of organophosphate intoxication
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Atropine + pralidoxime for regeneration of non-aged AChE.
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MOA pralidoxime
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Removes organophosphate group from AChE thus regenerating it. Aged AChE that have just a phosphate attached cannot be regenerated.
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Muscarinic blockers
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Atropine, tropicamide, ipratropium, scopolamine, benztropine
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Effects of muscarinic blockers
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Decreased salivary, bronchiolar and sweat secretions, mydriasis and cycloplegia, hyperthermia, tachychardia, sedation, urinary retention, constipation, hallucinations
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Rx of muscarinic blocker intoxication
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Physostigmine
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Uses of atropine
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Anesthesia, management of organophosphate toxicity
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Uses of propicamide
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Opthalmology
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Uses of ipratropium
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Inhaled in asthma and COPD. Doesn’t enter CNS.
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Uses of scopolamine
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Motion sickness, sedation, short-term memory block.
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Uses of benztropine
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Lipid-soluble, enters CNS. Used in parkinsonism and acute extrapyramidal symptoms of antipsychotics.
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Effects of ganglion blockers
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Reduce the predominant autonomic tone. PANS is dominant in heart, pupil, GI, GU and sphincters. SANS is dominant in blood vessels and sweat glands.
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Synthesis of catecholamines
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Tyrosine + tyrosine hydroxylase --> dopa + dopa decarboxylase --> dopamine + dopamine β hydroxylase --> norepinephrine + SAM + methyltransferase --> epinephrine
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MAO
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Located in outer mitochondrial membrane, degrades catecholamines by oxidative deamination. MAO-A: mainly in liver metabolizes NE, 5HT and tyramine. MAO-B mainly in brain, metabolizes DA.
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COMT
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Located in postsynaptic membrane, degrades catecholamines by methylations (requires SAM).
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Distribution of α1 receptors
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Pupil dilator muscle, arterioles of skin and viscera, veins, bladder trigone and sphincter, vas deferens, liver, kidney
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Distribution of α2 receptors
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Presynapsptic terminal, platelets, pancreas
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Distribution of β1 receptors
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Heart SA node, AV node, atrial and ventricular muscle, His-Purkinje, kidney
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Distribution of β2 receptors
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All blood vessels, uterus, bronchioles, skeletal muscle, liver pancreas
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Distribution of D1 receptors
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Renal, mesenteric, coronary vasculature
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α1 effects
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Mydriasis, increases TPR, diastolic pressure, afterload, venous return, preload, reflex bradycardia, urinary retention, ejaculation, glycogenolysis, decreases renin release
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α2 effects
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Decreases NE synthesis and release, promotes platelet aggregation, decreases insulin secretion
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β1 effects
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Increases HR, conduction velocity, contractility, CO, oxygen consumption and renin release
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β2 effects
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Vasodilation, decreases TPR, diastolic pressure and afterload, uterine relaxation, bronchodilation, increases glycogenolysis in liver and muscle, increases insulin secretion
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D1 effects
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Vasodilation of renal, mesenteric, coronary vasculatures, increases RBF, GFR
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α1 agonists
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Phenylephrine, methoxamine
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Uses of phenylephrine
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Nasal decongestant and opthalmologic mydriasis without cycloplegia
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α2 agonists
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Clonidine, methyldopa
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Uses of clonidine
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Mild to moderate hypertension
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Uses of methyldopa
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Mild to moderate hypertension
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Effects of β agonists on CV system
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β1: increase HR, CO, pulse pressure; β2: decrease TPR, BP.
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β agonists
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Isopreterenol, dobutamine
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β2 selective agonists
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Salmeterol, albuterol, terbutaline
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Uses of β2 selective agonists
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Asthma and ritodrine in premature labor
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Uses of isoproterenol
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β1=β2: used in bronchospasms, heart blocks and bradyarrhythmias. Side effects: flushing, angina, arrhythmias
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Uses of dobutamine
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β1 > β2: congestive heart failure
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Effects of norepinephrine on CV system
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Acts on α1 (increases TPR, BP), α2 and β1 (increases HR, CO, pulse pressure). Potential reflex bradycardia.
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Effects of low dose of epinephrine on CV and respiratory systems
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Acts on β1 (increases HR, SV, CO, pulse pressure), β2 (decreases TPR, BP, bronchodilation)
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Effects of medium dose epinephrine on CV and respiratory systems
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Acts on β1 (increases HR, SV, CO, pulse pressure), β2 (decreases TPR, BP, bronchodilation), α1 (increases TPR, BP)
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Effects of high dose epinephrine on CV and respiratory systems
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Acts on α1 (increases TPR, BP), β1 (increases HR, CO, pulse pressure), β2 (decreases TPR, BP, bronchodilation). Potential reflex bradycardia.
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Effect of adding α1 blocker to epinephrine
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Reverses hypertension to hypotension. Use this to differentiate from norepinephrine.
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Uses of epinephrine
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Cardiac arrest, adjunct to local anesthetic, hypotension, anaphylaxis, asthma
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Uses of norepinephrine
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Cardiac arrest, adjunct to local anesthetic, hypotension
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Indirect acting adrenergic agonists
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Releasers of catecolamines: Tyramine, amphetamines (methylphenidate), ephedrine. Reuptake inhibitors: cocaine, tricyclic antidepressants. MAO-A inhibitors interaction can cause hypertensive crisis.
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Effects of α blockers
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Decrease TPR and BP. May cause reflex tachychardia and salt/water retention.
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Uses of α blockers
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Hypertension, pheochromocytoma, BPH (selective α1 blocker)
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Nonselective α blockers
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Phentolamine, phenoxybenzamine
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Selective α1 blockers
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Prazosin, doxazosin, terazosin, tamsulosin
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Selective α2 blockers
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Yohimbe (used in hypotension and impotence), mirtazapine (depression)
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Effects of β1 blockers
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Decresed HR, SV, CO, renin, aqueous humor production
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Effects of β2 blockers
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Bronchospasm in asthmatics, vasospasm, decreased glycogenolysis, gluconeogenesis, increased LDLs, TGs
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Selective β1 blockers
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Acebutolol, atenolol, metroprolol
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Nonselective β blockers
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Pindolol, propranolol, timolol
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β blockers that raise blood lipids
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Atenolol (β1), metroprolol (β1), propranolol, timolol
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β blockers that cause the most sedation
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Propranolol, timolol
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β blockers with intrinsic sympathomimetic activity
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Act as partial agonists, less bradycardia, slight vasodilation, bronchodilation, minimal change in lipids: acebutolol, pindolol
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General uses of β blockers
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Angina, hypertension, post-MI
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β blockers used as antiarrhythmics
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Propranolol, acebutolol, esmolol
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Specific uses of timolol
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Glaucoma
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Specific uses of propranolol
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Migraine, thyrotoxicosis, performance anxiety, essential tremor
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Combined α1 and β blockers
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Labetalol, carvedilol. Used in CHF.
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Combined K channel and β blockers
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Sotalol. Class III antiarrhythmic.
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Ganglion blockers
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hexamethonium, mecamylamine
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