Question

Please, do not confuse the mechanism action of muscarinic receptor blockers like tiotropium and ipratropium in the lung with the mechanism of action of compounds like albuterol. Compared to acetylcholine, does the addition of the beta methyl group in bethanechol, increase or decrease its affinity and potency at nicotinic receptors ? Know the synthetic route of acetylcholine. Know the synthetic route of the catecholamines from tyrosine to epinephrine. Generally describe the enteric nervous system.

Answer 1

1) mechanism of action of muscarinic receptor blocker - these are long lasting antimuscarinic bronchidilator used in management of COPD ( chronic obstructive pulmonary disease ) and asthma. They act on M3 muss receptor located in airway to produce smooth muscle relaxation and bronchidilation.

Action of albuterol -- relax smooth muscle of airway. It activate beta -2- adrenergic receptor in lung which begins a cascade of actions that result in bronchidilation.

2) compared to ach addition of beta methyl group in bethanechol increase its affinity to muscarinic receptor. But have no potency towards nicotinic receptor.

3) synthetic route of acetylcholine -- synthesized from acetylcoenzyme A and choline by enzyme choline acetyltransferase.

4) synthesis of catecholamines -- Tyrosine is converted into DOPA (dihydoxyphenylalanine) by enzyme Tyrosine hydroxllase. It is rate limiting step.

DOPA decarboxylase convert DOPA into dopamine. Penylamine beta hydroxylase convert dopamine into norepinephrine. Phenylethanolamine N-methyltransferase convert norepinephrine into epinephrine.

5) Enteric nervous system -- or intrinsic nervous system is one of the main division of autonomic nervous system. And consist of mesh like network of neurons .

It include number of neural circuits that control motor functions, local blood flow, mucosal transport and secretion , modulate immune and endocrine functions.