10 Questions
What is the direct effect of Ach on the cardiac muscarinic receptors (M2)?
Slowing HR
What is the effect of Ach on the respiratory system?
Bronchospasm
Which receptor activation leads to vasodilation and lowering of blood pressure?
M3 receptors on vascular endothelium
What is the effect of Ach on the eye?
Miosis
What is the effect of Ach on the urinary system?
Contraction of the wall + relaxation of sphincter
Which cholinesterase inhibitor is used for the diagnosis of myasthenia gravis?
Edrophonium
What is the mechanism of action of Rivastigmine in Alzheimer's disease?
Reversible inhibition of central acetylcholinesterase
Which condition can be treated with Neostigmine?
Myasthenia gravis
What is the primary effect of irreversible anticholinesterases in organophosphorus poisoning?
Prolonged activation of acetylcholine receptors
Which neurotransmitter is targeted by Myasthenia gravis antibodies?
Nicotinic receptors in skeletal muscle
Study Notes
Cholinergic Agonists
- Cholinergic agonists can be classified into two categories: direct cholinergic agonists and indirect cholinergic agonists (anti-cholinesterases)
Direct Cholinergic Agonists
- Examples: Cholinomimetic alkaloids (e.g. pilocarpine)
- Pilocarpine is used topically for pre-operative treatment of closed-angle glaucoma
Indirect Cholinergic Agonists (Anti-Cholinesterases)
- Classification based on duration of action:
- Short-acting: Edrophonium
- Intermediate-acting: Neostigmine, Pyridostigmine, Rivastigmine
- Long-acting (Irreversible): Organophosphorus compounds
Therapeutic Uses of Reversible Cholinesterase Inhibitors
- Myasthenia gravis
- Alzheimer's disease
- Reversal of competitive neuromuscular blockers (NMB) to regain skeletal muscle activity at the end of surgery
Myasthenia Gravis
- A disease characterized by fluctuating weakness of voluntary muscles
Test your knowledge of the pharmacology of parasympathetic (cholinergic) agonists, including the clinical pharmacology, autonomic parasympathetic innervation, neuromuscular junction, central neurotransmitter, and pharmacological subtypes of cholinergic receptors.
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