Premium
The detection of differential β‐adrenoceptor blockade in the cat
Author(s) -
PARKES M. W.
Publication year - 1973
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1973.tb08256.x
Subject(s) - bronchodilatation , propranolol , tachycardia , medicine , adrenalectomy , endocrinology , bradycardia , anesthesia , chemistry , heart rate , blood pressure , asthma , salbutamol
Summary1 Tachycardia and bronchodilatation were produced by intravenous dimethyl‐phenylpiperazinium iodide (DMPP) in the spinal or pithed cat. Responses other than those involving β‐adrenoceptors were minimized by appropriate blocking agents. 2 With intact adrenals, both the tachycardia and bronchodilatation with 10 μg/kg DMPP were equal to those with 1 μg/kg adrenaline. 3 After adrenalectomy, tachycardia with 100 μg/kg DMPP was equal to that with 1·5 μg/kg adrenaline, but the bronchodilatation was equal to that with only 0·3 μg/kg. This difference may reflect the relative activity of the sympathetic supply to the organs. 4 After adrenalectomy, propranolol was 3 times as effective against bronchodilatation due to DMPP as against tachycardia. Practolol was inactive against bronchodilatation. 5 With intact adrenals, propranolol reduced both tachycardia and bronchodilatation due to DMPP equally. Propranolol also antagonized equally both effects of adrenaline in the pithed cat after adrenalectomy. 6 In the spinal cat, propranolol caused bradycardia and bronchoconstriction that persisted after adrenalectomy or pithing. It was reduced by pempidine and guanethidine and is attributed to spontaneous adrenergic neuronal activity. 7 The Appendix describes a device for cycle‐by‐cycle spirometry and correction for zero drift of a micromanometer, used in this study for the continuous recording of bronchial resistance.