Pharma 09: Muscarinic Signalling - Turning Up and Turning Down

This episode explores muscarinic receptor pharmacology as a lesson in nuance. Acetylcholine acting at muscarinic receptors governs secretion, smooth muscle tone, heart rate, and central signalling. We move beyond lists of agonists and antagonists to understand muscarinic effects as context-dependent responses shaped by receptor subtype, tissue distribution, and baseline autonomic tone. This framing explains why the same drug can soothe one organ while disturbing another.Key takeaways you’ll build and reuse throughout the series:* Muscarinic receptors as modulators: how M-receptor subtypes translate one neurotransmitter into diverse physiological effects.* Agonists and antagonists in context: why stimulation and blockade must be interpreted relative to baseline vagal tone.* Organ-specific responses: heart, lung, gut, eye, bladder, and glands as different “dial settings” of the same system.* Adverse effects as predictable extensions of mechanism, not random side-effects.* Clinical reasoning patterns: choosing muscarinic drugs by desired system effect, not by drug name alone. This is a public episode. If you'd like to discuss this with other subscribers or get access to bonus episodes, visit drmanaankarray.substack.com/subscribe