SELECT 5-selective antagonist

Phenylephrine (90) is a selective receptor agonist (+)-niguldipine (91) is a selective antagonist for the receptor. Pra2osin (92) and 5-methylurapidil (93) are nonselective a -receptor antagonists. CEC can differentiate receptors from the other receptors. Pra2osin has low and high affinity for and receptors, respectively. 

In the absence of selective antagonists, cytokines have been classified either on the basis of common functional properties or on the stmctural characteristics of their receptors. 

Unselective and ]1 selective antagonists are weU known, but there are few known selective K receptor antagonists. The first of these, norhinaltorphimine [105618-26-6] (nor BNI), has 400-fold selectivity for K over ]1 receptors and 250-fold for K over 5 (31). Two derivatives... 

In general, activation of alpha-1 adrenergic receptors causes a contraction of smooth muscle and of blood vessels, pilomotor muscles, dilator pupillae, vas deferens, nictitating membrane, splenic capsule, and sphincters of the intestine and urinary bladder and of the bile duct. An exception is the relaxation of the smooth muscle of the intestine. Prazosin [19216-56-9] indoramin [26844-12-2] and WB-4101 are relatively selective antagonists of these receptors. 

Beta receptors of the beta-1 subtype mediate an increase in heart rate and increased force of contraction they are also found in the central nervous system. E and NE are equaHy potent agonists and selective antagonists are atenolol [29122-68-7] and betaxolol [63659-18-7]. Beta-2 receptors are weH known for their involvement in relaxing bronchioles. E is a more potent agonist than NE procaterol [72332-33-3] is a selective agonist ICl 118551 and a-methylpropranolol are selective antagonists. A particular amine may act on both alpha and beta receptors or predominandy on one type. NE acts mainly on alpha-1, E on both alpha and beta, and isoprotemol [7683-59-2] almost exclusively on beta receptors. Numerous antagonists also differentiate between... 

Release of SP from neurons in the AP, NTS and dorsal vagal motor nucleus may play a role in vomiting induced by cytotoxics. Based on the relative effectiveness of selective antagonists of 5-HT3 receptors and NKi receptors against acute and delayed phases of cisplatin-induced vomiting, it has been suggested that serotonin has a greater role in the acute phase whereas SP has the major role in the delayed phase. 

Y2 receptors are characterised by an order of potency of NPY PYY > C-terminal fragment [Pro34]-substituted analogue > PP. BIIE 0246 ((S -iV2- 1 -[2-[4-[(i ,5)-5,11 -dihydro-6(6h)-oxodibenz[b,e]azepin-l 1 -yl]-l-piperazinyl]-2-oxoethyl]cyclopentyl]acetyl]-iV -[2-[l, 2-di-hydro-3,5-(4H)-dioxo-l, 2-diphenyl-3H-l, 2,4-ttiazol-4-yl]ethyl]-argininamide) is a Y2-selective antagonist with an affinity of 3 nM. 

Selective antagonists (naloxone) CTAP Naltrindole Nor-binaltorphimine J-113 397... 

Barusiban is a long-acting, selective antagonist of OTR that is in development for preterm labour. It has a 300-fold higher affinity for the OTR than for the Vi AR and hence more selective action than atosiban on myometrial tissues. The duration of action may be longer then that of atosiban, providing the convenience... 

In some cases, substrate racemization can be achieved by an appropriate change of a functional group. A good example of this strategy is the synthesis of acid 10, which is the key intermediate for roxifiban - a potent selective antagonist of the platelet plycoprotein Ilb/IIa receptor (Scheme 5.8) [27, 28]. 

---