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Antagonist properties of phentolamine at both presynaptic α2-adrenoceptors and presynaptic dopamine receptors using field stimulated right cat atria
- Source :
- European Journal of Pharmacology. 88:311-317
- Publication Year :
- 1983
- Publisher :
- Elsevier BV, 1983.
-
Abstract
- Phentolamine, which is considered a specific alpha-adrenoceptor antagonist, was tested for antagonist properties at presynaptic dopamine receptors and presynaptic alpha 2-adrenoceptors present on sympathetic nerve terminals in isolated right cat atria. Field stimulation induced a transient tachycardia which was inhibited by stimulation of presynaptic dopamine receptors using apomorphine or by stimulation of presynaptic alpha 2-adrenoceptors using clonidine. The presynaptic inhibitory effects of apomorphine were competitively antagonized by sulpiride, which is considered a specific dopamine receptor antagonist, and by phentolamine and yohimbine which are considered alpha-adrenoceptor antagonists. The presynaptic inhibitory effects of clonidine were competitively antagonized by phentolamine and yohimbine but not by sulpiride. pA2 values for phentolamine against apomorphine and phentolamine against clonidine suggest that phentolamine may be an antagonist at both presynaptic dopamine receptors and presynaptic alpha 2-adrenoceptors.
- Subjects :
- Male
medicine.medical_specialty
Apomorphine
Stimulation
In Vitro Techniques
Pharmacology
Clonidine
Receptors, Dopamine
Phentolamine
Internal medicine
medicine
Animals
Heart Atria
Dose-Response Relationship, Drug
Chemistry
Myocardium
Antagonist
Yohimbine
Receptors, Adrenergic, alpha
Electric Stimulation
Receptors, Adrenergic
Endocrinology
Dopamine receptor
Cats
Female
Sulpiride
medicine.drug
Subjects
Details
- ISSN :
- 00142999
- Volume :
- 88
- Database :
- OpenAIRE
- Journal :
- European Journal of Pharmacology
- Accession number :
- edsair.doi.dedup.....dd33116c06108754865858a42282477f
- Full Text :
- https://doi.org/10.1016/0014-2999(83)90581-2