Premium
SELECTIVE RESERPINE‐INDUCED SUPERSENSITIVITY OF THE POSITIVE INOTROPIC AND CHRONOTROPIC RESPONSES TO ISOPRENALINE AND SALBUTAMOL IN GUINEA‐PIG ISOLATED ATRIA
Author(s) -
BROADLEY K.J.,
LUMLEY P.
Publication year - 1977
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.1476-5381.1977.tb06976.x
Subject(s) - chronotropic , reserpine , isoprenaline , medicine , salbutamol , endocrinology , agonist , inotrope , chemistry , heart rate , receptor , stimulation , blood pressure , asthma
1 Dose‐response curves for the positive inotropic and chronotropic responses to isoprenaline were obtained in atria from untreated guinea‐pigs and those receiving various reserpine pretreatments. 2 Tension responses were unaffected, whereas rate responses were depressed by the lowest dose of reserpine (0.05 mg/kg i.p. at 24 hours). 3 With larger 24 h doses and a 3 day pretreatment, the rate and tension dose‐response curves were progressively displaced to the left, indicating supersensitivity which was greater for tension at each pretreatment. 4 No supersensitivity to histamine or Ca 2+ could be detected, leading to the conclusion that it was selective for the β‐adrenoceptor agonists possibly at the receptor level. 5 As an indication of the adrenergic neurone depleting effectiveness of each reserpine dosage, preparations were exposed to test doses of β‐phenylethylamine. 6 Salbutamol was a partial agonist in untreated atria, the maximum rate (63.3%) and tension (10.0%) responses being less than those for isoprenaline. In atria from reserpine pretreated animals the supersensitivity was revealed as an increase of this maximum compared with isoprenaline. 7 The significance of this observation in relation to the possible mechanism of the supersensitivity is discussed.