Different mechanisms of action of agents acting on beta-adrenoceptors in barium-stimulated and electrically-stimulated rat vas deferens

British Journal of Pharmacology
A Diaz-Toledo, A Jurkiewicz

Abstract

1. The relaxation induced by beta-adrenoceptor agonists in rat vas deferens was examined under two different experimental conditions: on electrically-induced twitch responses (35 V, 3 ms, 0.07 Hz), and on contractions induced by single doses of barium chloride (300 microM). The experiments were performed in vasa of reserpine-treated rats, after blockade of alpha-adrenoceptors and extraneuronal uptake with dibenamine (10 microM, 30 min), and neuronal uptake with cocaine (10 microM). 2. When twitch responses were used, the values of pD2, interpolated from cumulative concentration-response curves for isoprenaline (Iso), adrenaline (Ad), and noradrenaline (NA) showed a rank order of potency consistent with the presence of beta 2-adrenoceptors (Iso greater than Ad much greater than NA). 3. When twitch responses were used, the non-selective beta-antagonist, propranolol, caused a concentration-dependent parallel shift to the right of Iso concentration-response curves. Similar shifts were obtained by use of the beta 2-antagonist, isopropylmethoxamine (IMA), and higher doses of the beta 1-antagonist, practolol, according to the expectations from receptor occupation theory. Practolol presented the lowest value of pKB, 5.03, corroborating...Continue Reading

References

Feb 1, 1976·British Journal of Pharmacology·A Jurkiewicz, N H Jurkiewicz
Dec 1, 1985·Naunyn-Schmiedeberg's Archives of Pharmacology·J M MayK P Minneman
Dec 5, 1980·European Journal of Pharmacology·V J LottiP Kling
Jan 1, 1980·Laboratory Animals·V E Papaioannou, M F Festing
May 1, 1981·British Journal of Pharmacology·D Mackay
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Citations

Jul 4, 1996·European Journal of Pharmacology·N H JurkiewiczA Jurkiewicz
Jun 3, 2014·European Journal of Pharmacology·Bruno Palmieri de SouzaN H Jurkiewicz
Aug 12, 1998·The Tohoku Journal of Experimental Medicine·H InomataM Wakui
Sep 23, 1998·Australian and New Zealand Journal of Public Health·B JalaludinS Leeder

Related Concepts

Adrenergic beta-Agonists
Adrenergic beta-Antagonists
Metazoa
Barium
Electric Stimulation Technique
Inotropism
Muscle Relaxation Phase
Smooth Muscle
August Rats
Vas Deferens Structure

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