Welcome all to IS PHARMACOLOGY DIFFICULT Podcast! I am Dr Radhika Vijay, in today's episode I will be covering details about receptors more, specifically RECEPTOR SUBTYPES. Starting with examples for receptors of acetylcholine, namely Muscarinic (M), Nicotinic (N) receptors. These findings were confirmed with help of blockers. Ahlquist divided adrenergic receptors into alpha and beta based on different potencies of agonists. These all receptors are further subdivided in many subdivisions. There are multiple subtypes of receptors for all transmitters, hormones, etc. Receptor classification provides sound basis for different actions of closely related drugs. There are many criterias for subdivisions of drugs. First one is classical and old criteria , the Pharmacological criteria. Second criteria is Tissue distribution, which was confirmed with selective agonist and antagonists and molecular cloning. Third criteria is Ligand binding. Autoradiography has helped in mapping distribution of receptors in brain and many other organs. Fourth criteria is Transducer mechanism. Fifth and last on the list criteria is Molecular cloning. All the criterias are well accompanied with potent, apt, sufficiently important examples of many important different receptors and subtypes. Before calling it off for this episode, I will talk about Silent receptors. What is their essence and why they are named so, is their special classification justified, Please comment and let me know your opinion too, till next talkable talks, do follow me here, stay  tuned, do rate and review on Itunes , Apple podcasts, Thank you!!