GasGasGas - The FRCA Primary Exam Podcast VivaCast 007 - License to....? Adrenoceptors, Local anaesthetic, Classification Anti-Arrythmics
Feb 10, 2025
Explore the fascinating world of adrenoceptors and their diverse effects on heart rate and blood pressure. Discover the roles of local anaesthetics and how they block sodium channels to prevent action potentials. Delve into the Vaughan-Williams classification of anti-arrhythmics, including insights on beta blockers and calcium channel blockers. Learn practical exam tips on pharmacology and the importance of understanding G-protein subtypes for effective signalling. It's an exhilarating mix of complex concepts made digestible!
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Core Adrenoceptor Roles
- Adrenoceptors are G-protein coupled receptors responding to adrenaline and noradrenaline across tissues.
- Beta1 increases heart rate and stroke volume while alpha1 causes vasoconstriction and beta2 relaxes bronchial smooth muscle.
Less Obvious Adrenoceptor Effects
- Alpha2 receptors act presynaptically as negative feedback and can cause sedation and hypotension.
- Beta3 receptors influence metabolism and lipolysis, contributing to lactate rise with adrenaline.
Choose Vasopressors By Mechanism
- Use phenylephrine for pure alpha1 vasoconstriction and choose ephedrine or metaraminol when you need endogenous catecholamine release.
- Remember agents that release catecholamines (ephedrine, metaraminol) can tachyphylax with repeated use.