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Titolo:
RILMENIDINE REVEALS DIFFERENCES IN THE PHARMACOLOGICAL CHARACTERISTICS OF PREJUNCTIONAL ALPHA(2)-ADRENOCEPTORS IN THE GUINEA-PIG, RAT AND PIG
Autore:
ALI A; CHENG HY; TING KN; WILSON VG;
Indirizzi:
QUEENS MED CTR,SCH MED,SCH BIOMED SCI,CLIFTON BLVD NOTTINGHAM NG7 2UHENGLAND QUEENS MED CTR,SCH MED,SCH BIOMED SCI NOTTINGHAM NG7 2UH ENGLAND
Titolo Testata:
British Journal of Pharmacology
fascicolo: 1, volume: 125, anno: 1998,
pagine: 127 - 135
SICI:
0007-1188(1998)125:1<127:RRDITP>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
ALPHA-2-ADRENERGIC RECEPTOR SUBTYPES; POSTJUNCTIONAL ALPHA-ADRENOCEPTORS; ADRENERGIC-RECEPTOR; TAIL ARTERY; PRESYNAPTIC ALPHA(2)-ADRENOCEPTORS; IMIDAZOLINE RECEPTORS; SAPHENOUS-VEIN; BLOOD-VESSELS; BRAIN CORTEX; RABBIT;
Keywords:
RILMENIDINE; CLONIDINE; UK-14304; ALPHA(2A)-ADRENOCEPTORS; ALPHA(2D)-ADRENOCEPTORS; NEUROTRANSMISSION; URINARY BLADDER; GUINEA-PIG ILEUM; VAS DEFERENS; TAIL ARTERY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
46
Recensione:
Indirizzi per estratti:
Citazione:
A. Ali et al., "RILMENIDINE REVEALS DIFFERENCES IN THE PHARMACOLOGICAL CHARACTERISTICS OF PREJUNCTIONAL ALPHA(2)-ADRENOCEPTORS IN THE GUINEA-PIG, RAT AND PIG", British Journal of Pharmacology, 125(1), 1998, pp. 127-135

Abstract

1 The alpha(2A) and alpha(2D)-adrenoceptor subtypes are thought to bespecies homologs most easily differentiated on the basis of the potency of antagonists. In the present study we have compared the effect ofrilmenidine with two other selective alpha(2)-adrenoceptor agonists, UK-14304 (5-bromo-6- [2-imidazolin-2-ylamino]-quinoxaline) and clonidine, against electrically-evoked contractions in five isolated preparations from the rat, guinea-pig and pig, and, where possible, determinedthe receptor subtype involved. 2 UK-14034, clonidine and rilmenidine produced concentration-dependent inhibition of the electrically-evokedcontractions of the rat isolated vas deferens and tail artery and theguinea-pig ileum. These inhibitory effects were reversed by the selective alpha(2)-adrenoceptor antagonist, RX-811058 (1 mu M), except in the rat tail artery preparations where the remaining neurogenic response was inhibited; evidence for the involvement of 'innervated' alpha(2)-adrenoceptors. Both clonidine and UK-14304 produced concentration-dependent inhibition of responses in the porcine isolated tail artery andurinary bladder but clonidine was markedly less efficacious in these preparations. In contrast, rilmenidine failed to inhibit the neurogenic contractions in either preparation. 3 Although rilmenidine failed toelicit a detectable response in either the porcine isolated tail artery or urinary bladder, it (IO mu M and 30 mu M, respectively) competitively antagonised the inhibitory effects of UK-14304 with an estimateddissociation constant of(pK(B)) 5.82 and 5.93, respectively. 4 Prazosin (I mu M) failed to alter the effect of UK-14304 against neurogenic contractions in the porcine isolated urinary bladder, while rauwolscine (pK(B) 8.87) was 10 fold more potent than phentolamine (pK(B) 7.56). On the other hand, phentolamine (pK(B) 8.42) was only marginally morepotent than rauwolscine (pK 8.05) against clonidine-induced inhibition of electrically-evoked contractions of the guinea-pig isolated ileum. This pharmacological evidence with antagonists supports the presenceof alpha(2D)- adrenoceptors in the rat and guinea-pig and the alpha(2A)-adrenoceptors in the pig. 5 We have demonstrated that rilmenidine, unlike clonidine and UK-14304, is devoid of any agonist activity at prejunctional alpha(2A)-adrenoceptors in the pig, but is an efficacious agonist at alpha(2D)-adrenoceptors in the rat and guinea-pig.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/12/20 alle ore 08:04:16