Adrenergic Receptors
Adrenergic receptors (adrenoceptors) are classified into two main groups, α and β. The α group has been further divided into α1 and α2 which are, in turn, subdivided into α1A, α1B, α1D and α2A, α2B and α2C respectively. β-Adrenoceptors are currently classified into β1, β2 and β3 subgroups with a putative β4 receptor, as yet uncloned but exhibiting a distinct pharmacological profile.
Allosteric GPCR Pharmacology Poster
G protein-coupled receptors (GPCRs) are intrinsically allosteric proteins. This poster provides insights into allosteric mechanisms of GPCR biology, highlighting key facets of GPCR allostery and therapeutic applications of allosteric modulators.
GPCR Efficacy and Biased Agonism Poster
GPCRs can interact with multiple distinct transducers or regulatory proteins and these can be preferentially engaged in an agonist-specific manner giving rise to biased agonism. This poster discusses cutting edge GPCR signaling pharmacology and highlights therapeutic applications of biased agonism.
α1-Adrenergic Receptor Data
| Receptor Subtype | α1A | α1B | α1D |
|---|---|---|---|
| Transduction Mechanism | Activates Gp/q, ↑ PI turnover, ↑[Ca2+]i.c., activates voltage-gated Ca2+ channels | ||
| Localization | CNS, heart, liver, prostate, urethra | CNS, somatic arteries and veins, spleen, kidney | CNS, aorta, bladder, prostate |
| Tissue Function | Smooth muscle contraction, myocyte hypertrophy, activation of sarcolemmal Na+-H+ exchanger | Smooth muscle contraction, cardiac growth and contractile function | Smooth muscle contraction |
| Selective Agonists | A 61603 (1052) Oxymetazoline (1142) | Unknown | Unknown |
| Non-subtype Selective Agonists | Cirazoline (0888) (R)-(-)-Phenylephrine hydrochloride (2838) | Cirazoline (0888) (R)-(-)-Phenylephrine hydrochloride (2838) | Cirazoline (0888) (R)-(-)-Phenylephrine hydrochloride (2838) |
| Selective Antagonists | RS 17053 (0985) RS 100329 (1325) SNAP 5089 (2398) WB 4101 (0946) Tamsulosin (3050) | Rec 15/2615 (3284) | BMY 7378 (1006) |
| Non-subtype Selective Antagonists | Prazosin (0623) Doxazosin (2964) Alfuzosin (3305) | Prazosin (0623) Doxazosin (2964) Alfuzosin (3305) | Prazosin (0623) Doxazosin (2964) Alfuzosin (3305) |
α2-Adrenergic Receptor Data
| Receptor Subtype | α2A | α2B | α2C |
|---|---|---|---|
| Transduction Mechanism | Activates Gi/o, ↓ PI turnover, inhibits voltage-gated Ca2+ channels, activates voltage-gated Ca2+ dependent K+ channels | ||
| Localization | Brain, spleen, kidney, aorta, lung, skeletal muscle, heart, liver | Spleen, kidney, aorta, lung, skeletal muscle, heart, liver | Brain, kidney, aorta, lung, skeletal muscle, heart, spleen |
| Tissue Function | Hypotension, sedation, analgesia, hypothermia, anesthesia, inhibition of noradrenalin release | Vasoconstriction | Presynaptic inhibition of noradrenalin release |
| Selective Agonists | Oxymetazoline* (1142) Guanfacine (1030) | Unknown | (R)-(+)-m-Nitrobiphenyline oxalate ST 91 (2638) |
| Non-subtype Selective Agonists | Clonidine (0690) UK 14,304 tartrate (2466) | Clonidine (0690) UK 14,304 tartrate (2466) | Clonidine (0690) UK 14,304 tartrate (2466) |
| Selective Antagonists | BRL 44408 (1133) | ARC (0928) Imiloxan (0986) Prazosin (0623) | JP 1302 (2666) Rauwolscine† (0891) |
| Non-subtype Selective Antagonists | RS 79948 (0987) Yohimbine (1127) Efaroxan (0792) Idazoxan (0793) | RS 79948 (0987) Yohimbine (1127) Efaroxan (0792) Idazoxan (0793) | RS 79948 (0987) Yohimbine (1127) Efaroxan (0792) Idazoxan (0793) |
*partial agonist
†10-20 fold selective for α2C
β-Adrenergic Receptor Data
| Receptor Subtype | β1 | β2 | β3 |
|---|---|---|---|
| Transduction Mechanism | ↑ Adenylyl cyclase (via Gs) | ||
| Localization | CNS, heart, coronary artery, lung, spleen, kidney, liver, muscle | CNS, heart, lung, spleen, kidney, liver, skeletal muscle | Adipose tissue, gall bladder, small intestines, stomach, prostate, left atrium, bladder, vascular endothelium |
| Tissue Function | Tachycardia, coronary vasodilation, increase heart contractile force, apoptosis, relaxation of colon and esophagus | Hypotension, smooth muscle relaxation e.g. bronchodilation, inhibition of apoptosis | Lipolysis, glucose uptake, cardioinhibition, relaxation of colon, esophagus and bladder |
| Key Compounds | Ki values (nM) | |||
|---|---|---|---|---|
| Agonists | BRL 37344 (0948) CGP 12177* (1134) Cimaterol (0435) Pindolol (0994) Salbutamol (0634) | 1750 0.9 - 3.4 - | 1120 4 - 2.3 - | 287 88 4700 11 53000 |
| Antagonists | ICI 118,551 (0821) L-748,337 (2760) | 120 390 | 1.2 204 | 257 4 |
*β3 partial agonist, β1/β2
References
Bylund et al (1994) Pharmacol.Rev. 46 121.Hieble et al (1995) J.Med.Chem. 38 3415. Strosberg and Pietri-Rouxel (1996) TiPS 17 373. Docherty et al (1998) Eur.J.Pharmacol. 361 1. Robinson and Hudson (1998) Tocris Reviews. No. 8.