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  • Title: Is there any evidence of beta 1-adrenoceptors mediating relaxation of guinea-pig lung parenchyma?
    Author: Johansson LH, Persson H, Rosengren E.
    Journal: Acta Pharmacol Toxicol (Copenh); 1984 May; 54(5):346-51. PubMed ID: 6147065.
    Abstract:
    We tried to find functional evidence for the existence of beta 1- and beta 2-adrenoceptors in the isolated guinea-pig lung parenchymal strip preparation, using potent and selective beta 1- and beta 2-adrenoceptor stimulation. To obtain potent beta 1-adrenoceptor stimulation the nonselective beta-adrenoceptor agonist isoprenaline was combined with a highly selective beta 2-adrenoceptor antagonist--ICI 118,551. Potent beta 2-adrenoceptor stimulation was obtained by procaterol. Practolol (beta 1-adrenoceptor antagonist) and ICI 118,551 were used as antagonists. ICI 118,551, 10(-7) mol/l, shifted the concentration response (C/R) curve of isoprenaline to a higher concentration range. The C/R curve of procaterol was shifted in the same way and to the same degree by this concentration of ICI 118,551. The C/R curve of isoprenaline was not further shifted after blockade with a combination of ICI 118,551, 10(-7) mol/l, and practolol, 10(-6). However, in the trachea preparation, a tissue containing both beta 1- and beta 2-adrenoceptors, there was a further shift of the C/R curve of isoprenaline to a higher concentration range after blockade with a combination of ICI 118,551 and practolol in the concentrations given above. In this preparation the shift of the C/R curve of procaterol was ten times greater than that of isoprenaline after blockade with ICI 118,551, 10(-7) mol/l. We conclude that it is possible to characterize small fractions of beta 1-adrenoceptors coexisting with beta 2-adrenoceptors with the technique used. Furthermore there is still no functional evidence of the existence of beta 1-adrenoceptors in the lung parenchyma.
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