BIOM20002 Lecture Notes - Lecture 31: Heparin, Isoprenaline, Adrenergic Receptor
Document Summary
Sympathetic drive: release of na on beta receptors of cardiac cells to increase rate of contraction to increase cardiac output to increase blood pressure. Over time exposure to na decreases beta1 receptors. Ec50 for isoprenaline has shifted to the right. Prenalterol is now barely able to elicit a response. In prenalterol: even though it occupies all receptors there isn"t enough to elicit a response. Need high affinity: occupies receptors at low conc. Need lots of receptors: so given a fraction of receptors occupied you will have more receptors occupied. Efficient stimulus response coupling: converts stimulus to a response. Antagonising molecule directly binds to or destroys the other molecule. Antibodies do it e. g. protamine antagonism of heparin. Protamine interacts with it and neutralises heparins active site. Only one drug molecule can bind to the active site of a receptor at a time. Antagonist and agonist act at same site on receptor. Surmountable (if you have enough agonist it can displace antagonist)
