DEMONSTRATION OF BOTH β1‐ AND β2‐ADRENOCEPTORS MEDIATING RELAXATION OF ISOLATED RING PREPARATIONS OF RAT PULMONARY ARTERY
Open Access
- 1 November 1981
- journal article
- Published by Wiley in British Journal of Pharmacology
- Vol. 74 (3), 547-552
- https://doi.org/10.1111/j.1476-5381.1981.tb10463.x
Abstract
1 Cumulative concentration-response (relaxation) curves to three β-adrenoceptor agonists, fenoterol (β2-selective), isoprenaline (non-selective) and noradrenaline (β1-selective) were obtained on isolated ring preparations of rat pulmonary artery contracted with 15 mM KCl. α-Adrenoceptors and neuronal and extraneuronal uptakes were blocked with phenoxybenzamine. The agonist concentration-response curves were reproducible. 2 Responses to each of the three agonists could be blocked by the β-adrenoceptor antagonists atenolol (β1-selective) or ICI 118,551 (β2-selective) confirming the presence of β-adrenoceptors. 3 The relative potencies of the agonists were isoprenaline: fenoterol: noradrenaline = 100: 38: 1.4. This indicated that the predominant β-adrenoceptor type was β2. 4 Schild plots were obtained for atenolol and ICI 118,551 using the three different agonists. For each antagonist the location of the Schild plot varied depending on which agonist was used. This indicated that the β-adrenoceptor population mediating relaxation responses to β-adrenoceptor agonists was not homogeneous. 5 Atenolol was most potent when noradrenaline was the agonist and ICI 118,551 was most potent when fenoterol was the agonist. 6 It is concluded that isolated pulmonary artery ring preparations of the rat contain a mixed population of β1- and β2-adrenoceptors both mediating relaxation.Keywords
This publication has 22 references indexed in Scilit:
- Evidence that ICI 118, 551 is a potent, highly beta2-selective adrenoceptor antagonist and can be used to characterize beta-adrenoceptor populations in tissuesLife Sciences, 1980
- pA2 values of selective β-adrenoceptor antagonists on isolated atria demonstrate a species difference in the β-adrenoceptor populations mediating chronotropic responses in cat and guinea-pigJournal of Pharmacy and Pharmacology, 1979
- Beta1 and beta2 receptor mechanisms in rat jugular veins: Differences between norepinephrine and isoproterenol-induced relaxationLife Sciences, 1978
- Vasodilatation and modulation of vasoconstriction in canine subcutaneous adipose tissue caused by activation of β-adrenoceptorsActa Physiologica Scandinavica, 1978
- The relationship between age and relaxation of vascular smooth muscle in the rabbit and rat.Circulation Research, 1976
- Pharmacological Characterization of Adrenergic Alpha and Beta Receptors Mediating the Vasomotor Responses of Cerebral Arteries Ir VitroCirculation Research, 1974
- Response of the Rabbit Coronary Arteries to Autonomic AgentsJournal of Vascular Research, 1974
- Differentiated blockade of the chronotropic effects of various adrenergic stimuli in the cat heartLife Sciences, 1972
- Differentiation of receptors responsive to isoproterenolLife Sciences, 1967
- Differentiation of Receptor Systems activated by Sympathomimetic AminesNature, 1967