Yohimbine antagonises α1A- and α1D-adrenoceptor mediated components in addition to the α2A-adrenoceptor component to pressor responses in the pithed rat
| Autor: | James R. Docherty |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Agonist
Male Xylazine medicine.medical_specialty medicine.drug_class Pharmacology Amidephrine Piperazines chemistry.chemical_compound Phenylephrine Idazoxan Receptors Adrenergic alpha-2 Internal medicine Receptors Adrenergic alpha-1 Prazosin medicine Adrenergic alpha-2 Receptor Agonists Potency Animals Drug Interactions Rats Wistar Dose-Response Relationship Drug Chemistry Antagonist Yohimbine Adrenergic alpha-2 Receptor Antagonists Rats Endocrinology Ethanolamines Vasoconstriction Adrenergic alpha-1 Receptor Antagonists Adrenergic alpha-1 Receptor Agonists Thymine medicine.drug |
| Zdroj: | European journal of pharmacology. 679(1-3) |
| ISSN: | 1879-0712 |
| Popis: | We have recently shown that responses to pressor nerve stimulation in the pithed rat are mediated by α(1A)- and α(1D)-adrenoceptors, with no evidence for α(2)-adrenoceptor involvement, and that responses previously identified as α(2)-adrenoceptor mediated are actually α(1D)-adrenoceptor mediated. We have now re-examined the subtypes of α-adrenoceptor involved in pressor responses produced by exogenous agonists in the pithed rat preparation to confirm whether α(2)-adrenoceptors are involved in these responses. The α(2)-adrenoceptor and α(1D)-adrenoceptor antagonist yohimbine (1mg/kg) and the α(2A)-adrenoceptor antagonist methoxy-idazoxan (5 mg/kg) significantly shifted, but the α(1D)-adrenoceptor antagonist BMY 7378 (8-[2-[4-(methoxyphenyl)-1-piperazinyl]ethyl]-8-azaspir o[4.5]decane-7,9-dione dihydrochloride) (1 mg/kg) did not affect, the pressor potency of the α(2)-adrenoceptor agonist xylazine. α(1)-adrenoceptor antagonists showed low potency against pressor responses to xylazine. The pressor potency of the α(1)-adrenoceptor agonist amidephrine was not affected by BMY 3778 (1 mg/kg) but significantly shifted by prazosin (0.01 mg/kg) and by yohimbine (1 mg/kg). In contrast, the pressor potency of phenylephrine was significantly shifted by both yohimbine and BMY 7378 (1 mg/kg), but to a greater extent by the α(1A)-adrenoceptor antagonist RS 100329 (5-Methyl-3-[3-[3-[4-[2-(2,2,2,trifluroethoxy) phenyl]-1-piperazinyl]propyl]-2,4-(1H,3H)-pyrimidinedione] hydrochloride) (0.1 mg/kg). In conclusion, we have identified and separated α(1A)-, α(1D)- and α(2A)-adrenoceptor antagonist actions of yohimbine against pressor responses. Pressor responses to exogenous agonists in the pithed rat involve both α(1A)- and α(1D)-adrenoceptors and in addition, α(2A)-adrenoceptors. |
| Databáze: | OpenAIRE |
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