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

2013; University of Veterinary and Pharmaceutical Sciences, Brno; Volume: 82; Issue: 3 Linguagem: Inglês

10.2754/avb201382030331

1801-7576

Jan Gnus, A. Czerski, Stanisław Ferenc, Wojciech Zawadzki, Wojciech Witkiewicz, Agnieszka Rusiecka, Jolanta Bujok, Willy Hauzer, Maciej Janeczek, Aleksander Chrószcz,

Hormonal Regulation and Hypertension

Investigation of the effect of α 1 -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 α 1 -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 α 1 -adrenergic receptor agonist phenylephrine without pre-incubation or after incubation in α 1 -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 (α 1A -adrenergic receptor antagonist) followed by phentolamine and prazosin (non-selective α 1 -adrenergic receptor antagonists); BMY 7378 (α 1D -adrenergic receptor antagonist), cyclazosin and L-765.314 (α 1B -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 α 1A receptors are the most potent in producing rabbit abdominal aorta contraction, while α 1B and α 1D subtypes are less effective.