Pharmacological Modulation Of ANS

Question 1

Define how adrenoceptors are classified

Answer 1

• For α receptors, noradrenaline is more effective than adrenaline, which is more effective than isoprenaline (synthetic!)
• NA > A > Iso
• For β receptors, isoprenaline is more effective than adrenaline, which is more effective than noradrenaline
• Iso > A > NA
• These two groups have been further subdivided by the development of selective antagonists and molecular biological techniques. So you also have—
• α1 ¬and α2
• β1, β2 and β3
• All adrenoceptors have 7-transmembrane domains and associate with GTP binding proteins, so they are G-protein coupled receptors.
• The individual α and β pathways utilise different secondary messenger pathways