Information needed for calculations Specific activity = 19.5 Ci mmolˉ1 1 Ci = 2.22 x 10ˉ12 dpm (Disintegrations per minute) 1 mmol = 19.5 x (2.22 x 10ˉ12) dpm

Information needed for calculations II Calculate the total number moles bound in each tube = tube dpm 19.5 x (2.22 x 10ˉ12 dpm) e.g. if tubes dpm = 788 No. mmol = 788 = 1.82 x 10ˉ11 mmol / 1.82 x 10ˉ14 mol

Quantify receptor affinity for a drug and so classify receptor types Use 1: Quantify receptor affinity for a drug and so classify receptor types 14 receptors identified for 5-hydroxytryptamine (5-HT) all with a radioactive ligand for ligand binding analysis 5-HT1A,B 5-HT2A,B 5-HT3 5-HT4 2 cannabinoid receptors, each with a radioactive ligand CB1 CB2

Use 2: Find molecular shape of drug binding pocket : drugs by computer design? 7 6 5 1 antagonist agonist 2 3 4

Selective drug target for analgesia?? Use 3: Receptor localisation and expression levels in normal/diseased organs and cells P2X3 receptor (an extracellular ATP receptor) found only in sensory neurone C-fibres Selective drug target for analgesia??