Predicting in vivo cardiovascular properties of β-blockers from cellular assays: a quantative comparison of cellular and cardiovascular pharmacological responses

Baker, Jillian G. and Kemp, Philip and March, Julie and Fretwell, Laurice and Hill, Stephen J. and Gardiner, Sheila M. (2011) Predicting in vivo cardiovascular properties of β-blockers from cellular assays: a quantative comparison of cellular and cardiovascular pharmacological responses. FASEB Journal, 25 (12). pp. 4486-4497. ISSN 0892-6638

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Abstract

β-Adrenoceptor antagonists differ in their degree of partial agonism. In vitro assays have provided information on ligand affinity, selectivity, and intrinsic efficacy. However, the extent to which these properties are manifest in vivo is less clear. Conscious freely moving rats, instrumented for measurement of heart rate (β1; HR) and hindquarters vascular conductance (β2; HVC) were used to measure receptor selectivity and ligand efficacy in vivo. CGP 20712A caused a dose-dependent decrease in basal HR (P<0.05, ANOVA) at 5 doses between 6.7 and 670 μg/kg (i.v.) and shifted the dose-response curve for isoprenaline to higher agonist concentrations without altering HVC responses. In contrast, at doses of 67 μg/kg (i.v.) and above, ICI 118551 substantially reduced the HVC response to isoprenaline without affecting HR responses. ZD 7114, xamoterol, and bucindolol significantly increased basal HR (ΔHR: +122±12, +129±11, and +59±11 beats/min, respectively; n=6), whereas other β-blockers caused significant reductions (all at 2 mg/kg i.v.). The agonist effects of xamoterol and ZD 7114 were equivalent to that of the highest dose of isoprenaline. Bucindolol, however, significantly antagonized the response to the highest doses isoprenaline. An excellent correlation was obtained between in vivo and in vitro measures of β1-adrenoceptor efficacy (R2=0.93; P<0.0001).—Baker, J. G., Kemp, P., March, J., Fretwell, L., Hill, S. J., Gardiner, S. M. Predicting in vivo cardiovascular properties of β-blockers from cellular assays: a quantitative comparison of cellular and cardiovascular pharmacological responses.

Item Type: Article
Keywords: β-adrenoceptor, Partial agonism, Intrinsic sympathomimetic activity, Heart rate, Vascular conductance
Schools/Departments: University of Nottingham UK Campus > Faculty of Medicine and Health Sciences > School of Life Sciences > School of Biomedical Sciences
Identification Number: https://doi.org/10.1096/fj.11-192435
Depositing User: Wahid, Ms. Haleema
Date Deposited: 16 Apr 2014 09:06
Last Modified: 13 Sep 2016 19:24
URI: http://eprints.nottingham.ac.uk/id/eprint/2359

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