Acta Vet. Brno 2013, 82: 331-336

Role of α1-adrenergic receptor subtypes in contractility of the rabbit abdominal aorta in vitro

Jan Gnus1, Albert Czerski1,2, Stanisław Ferenc1, Wojciech Zawadzki1,2, Wojciech Witkiewicz1, Agnieszka Rusiecka1,2, Jolanta Bujok1,2, Willy Hauzer1, Maciej Janeczek2, Aleksander Chrószcz2

1General and Vascular Surgery Ward of Regional Specialist Hospital, Research and Development Centre in Wroclaw, Wrocław, Poland
2Wrocław University of Environmental and Life Sciences, Faculty of Veterinary Medicine, Department of Animal Physiology and Biostructure, Wrocław, Poland

Investigation of the effect of α1-adrenergic receptor subtypes on the contraction of the abdominal aorta will allow for more effective treatment of hypertension by use of selective antagonists. The aim of the study was to evaluate the participation of α1-adrenergic receptor subtypes in the contractility of the aortic smooth muscle cells in rabbits. The in vitro experiments were performed in isolated tissue preparations from 30 adult female New Zealand rabbits. The abdominal aortic sections were placed in organ bath chambers and contracted with increasing doses of non-selective α1-adrenergic receptor agonist phenylephrine without pre-incubation or after incubation in α1-adrenergic receptor subtype-selective or non-selective antagonists. Separate sections were incubated with increasing concentrations of antagonists. Phenylephrine caused maximal rise in arterial smooth muscle tone to 4.75 ± 0.47 mN. The most potent in blocking phenylephrine induced contraction was 5-metylurapidil (α1A-adrenergic receptor antagonist) followed by phentolamine and prazosin (non-selective α1-adrenergic receptor antagonists); BMY 7378 (α1D-adrenergic receptor antagonist), cyclazosin and L-765.314 (α1B-adrenergic receptor antagonists) were less effective. All antagonists, except BMY 7378 elicited relaxation of non-precontracted aorta in dose dependent manner. Our results indicate that postsynaptic α1A receptors are the most potent in producing rabbit abdominal aorta contraction, while α1B and α1D subtypes are less effective.


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