22 Questions
Which of the following drugs is a β1 selective agonist?
Dobutamine
What is the effect of β2 selective agonists on blood vessels?
Vasodilation
Which of the following is an α antagonist?
Phentolamine
What is the mechanism of action of receptor agonists?
they mimic the action of transmitters
Which of the following drugs is used for congestive heart failure and cardiogenic shock?
Dobutamine
What is the therapeutic application of β2 selective agonists?
Treatment of asthma
What is the effect of Botulinum toxin on the release of neurotransmitter ACh?
Prevents release
What is the therapeutic application of ephedrine?
Nasal decongestion and asthma
What is the mechanism of action of cocaine?
Re-uptake inhibitor
What is the effect of alpha (α) receptors on blood vessels?
Vasoconstriction
What is the therapeutic application of galanthamine?
Alzheimer's disease
What is the effect of phenelzine on neurotransmission?
Inhibits the enzymatic inactivation of NA
What is the primary mechanism of action of cocaine in noradrenergic neurotransmission?
Inhibition of reuptake
Which of the following receptors is responsible for smooth muscle contraction in blood vessels?
Alpha 1 receptor
What is the effect of isoprenaline on peripheral resistance?
Decreases peripheral resistance
Which of the following drugs is a selective alpha 2 agonist?
Clonidine
What is the therapeutic application of salbutamol?
Treatment of asthma
Which of the following enzymes is responsible for the degradation of noradrenaline?
Monoamine oxidase (MAO)
What is the effect of noradrenaline on peripheral resistance?
Increases peripheral resistance
Which of the following receptors is responsible for smooth muscle relaxation in the respiratory tract?
Beta 2 receptor
What is the mechanism of action of phenelzine?
Inhibition of monoamine oxidase
Which of the following drugs is a selective beta 1 agonist?
Dobutamine
Study Notes
Adrenergic Receptors and Neurotransmission
- Adrenergic receptors are classified into two types: alpha (α) and beta (β)
- α receptors: NA > A > Isoprenaline
- β receptors: Isoprenaline > A > NA
- α receptors are further divided into α1 and α2, and β receptors into β1, β2, and β3
- Each subtype has a different second messenger response
Neurotransmitter Release and Re-uptake
- Neurotransmitter release: ACh, NA, tyramine, ephedrine, and amphetamine promote release
- Re-uptake inhibitors: cocaine, imipramine; inhibit uptake 1, increase NA effect
- Uses: cocaine (local anaesthetic), imipramine (depression)
- Side effects: cocaine (drug dependence), imipramine (atropine-like effects)
Inhibitors of Enzymatic Inactivation
- ACh esterase inhibitors: galanthamine; inhibit ACh esterase in synaptic cleft, prolong ACh action
- MAO inhibitors: phenelzine; inhibit monoamine oxidase in presynaptic terminal, increase stored pool
- Uses: galanthamine (Alzheimer's disease), phenelzine (depression)
- Side effects: phenelzine (cheese reaction)
Adrenergic Transmission and Receptors
- Noradrenaline receptors: α1, α2, β1, β2, β3
- α1: inositol triphosphate (IP3), diacylglycerol (DAG)
- α2: ↓ cAMP
- β1: ↑ cAMP
- β2: ↑ cAMP
- β3: unknown
Structure-Activity Relationships (SAR)
- Increase size of substituents on N atom: potent β agonists, less affinity for UT1 and MAO
- Addition of α-methyl group: α selective, resistant to MAO, still susceptible to UT1
- Removal of β -OH: greatly reduced interaction with α and β receptors
- Substitute or replace catechol -OH groups: not degraded by COMT, still susceptible to UT1
Adrenergic Receptors in Peripheral Tissues
- Cardiovascular system: α receptors (smooth muscle contraction), β receptors (smooth muscle relaxation)
- Heart: β1 receptors (+ve chronotrophic and inotrophic effects)
- Eye: α receptors (radial papillary dilation muscle), β receptors (ciliary muscle relaxation)
- Respiratory tract: β2 receptors (bronchial muscle relaxation, bronchodilation)
- Gastrointestinal tract: α receptors (presynaptic on cholinergic terminals, ↓ release of ACh), β receptors (smooth muscle relaxation)
Adrenergic Agonists and Antagonists
- Receptor agonism (mimics action of NorAdr): NorAdr, α phenylephrine, methoramine (α1), Clonidine, α-methyl-NorAdr (α2), isoprenaline, Adr (β), prenalterol (β1), salbutamol, terbutaline (β2)
- Receptor antagonism (blocks action of NorAdr): atropine (M antagonist), phentolamine (α antagonist), propranolol (β antagonist)
Test your knowledge of adrenergic and cholinergic receptors, including agonists and antagonists, and their effects on the body. Learn about the different types of receptors and their responses to various drugs. Assess your understanding of pharmacology and its applications in medicine.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
