Relaxation of cat trachea by β‐adrenoceptor agonists can be mediated by both β1‐ and β2‐adrenoceptors and potentiated by inhibitors of extraneuronal uptake
Open Access
- 1 February 1983
- journal article
- research article
- Published by Wiley in British Journal of Pharmacology
- Vol. 78 (2), 417-424
- https://doi.org/10.1111/j.1476-5381.1983.tb09406.x
Abstract
1 Responses (relaxation) to the β-adrenoceptor agonists, isoprenaline, fenoterol or noradrenaline, were obtained on cat tracheal preparations contracted with a submaximal concentration of carbachol (0.5 μm). 2 The relative potencies of isoprenaline: fenoterol: noradrenaline were 100:8.1:10.7. From this, it was concluded that responses were mediated predominantly by β1-adrenoceptors but that a minor population of β2-adrenoceptors might also be involved. 3 Schild plots for the selective antagonists atenolol (β1-selective) or ICI 118, 551 (β2-selective) were in different locations, i.e. were separated, depending on whether the antagonist was antagonizing noradrenaline or fenoterol. This supported the conclusion that β2- as well as β1-adrenoceptors were involved in mediating the response. In this respect, cat trachea resembles cat atria (rate responses). 4 In the presence of atenolol the concentration-response curves to fenoterol became biphasic. This was interpreted as indicating that the β2-adrenoceptors were too few in number to elicit a maximum tissue response. 5 Responses to isoprenaline of cat trachea were potentiated by the extraneuronal uptake inhibitor drugs, corticosterone and metanephrine. This indicated that extraneuronal uptake could modulate β-adrenoceptor-mediated responses (relaxation) of cat trachea. 6 Cat trachea resembles guinea-pig trachea in that (i) the β-adrenoceptor population mediating relaxation is mixed (β1 + β2) and (ii) responses to isoprenaline are modulated by its extraneuronal uptake. However, cat trachea differs from guinea-pig trachea in that the predominant β-adrenoceptor sub-type is β1 not β2.Keywords
This publication has 18 references indexed in Scilit:
- Postsynaptic Adrenergic Receptor Mechanisms in Vascular Smooth Muscle1Published by S. Karger AG ,2015
- ERRORS IN THE MEASUREMENT OF AGONIST POTENCY‐RATIOS PRODUCED BY UPTAKE PROCESSES: A GENERAL MODEL APPLIED TO β‐ADRENOCEPTOR AGONISTSBritish Journal of Pharmacology, 1980
- The importance of choice of agonist in studies designed to predict ? 2:? 1 adrenoceptor selectivity of antagonists from pA2 values on guinea-pig trachea and atriaNaunyn-Schmiedebergs Archiv für experimentelle Pathologie und Pharmakologie, 1979
- THE EXTRANEURONAL ACCUMULATION OF ISOPRENALINE IN TRACHEA AND ATRIA OF GUINEA-PIG AND CAT: A FLUORESCENCE HISTOCHEMICAL STUDYBritish Journal of Pharmacology, 1979
- THE USE OF FUNCTIONAL ANTAGONISM TO DETERMINE WHETHER β‐ADRENOCEPTOR AGONISTS MUST HAVE A LOWER EFFICACY THAN ISOPRENALINE TO BE TRACHEA‐ATRIA SELECTIVE in vitro IN GUINEA‐PIGSBritish Journal of Pharmacology, 1977
- THE CAT LUNG STRIP AS AN in vitro PREPARATION OF PERIPHERAL AIRWAYS: A COMPARISON OF β‐ADRENOCEPTOR AGONISTS, AUTACOIDS AND ANAPHYLACTIC CHALLENGE ON THE LUNG STRIP AND TRACHEABritish Journal of Pharmacology, 1976
- THE CONTRIBUTION OF EXTRANEURONAL UPTAKE TO THE TRACHEA‐BLOOD VESSEL SELECTIVITY OF β‐ADRENOCEPTOR STIMULANTS in vitro IN GUINEA‐PIGSBritish Journal of Pharmacology, 1976
- The effects of hydrocortisone on responses to and extraneuronal uptake of (?)-isoprenaline in cat and guinea-pig atriaClinical and Experimental Pharmacology and Physiology, 1976
- Differentiation of β-adrenoreceptors by the use of blocking agentsJournal of Pharmacy and Pharmacology, 1970
- SOME QUANTITATIVE USES OF DRUG ANTAGONISTSBritish Journal of Pharmacology and Chemotherapy, 1959