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Involvement of α‐adrenoreceptors in the regulation of omasal cyclic myoelectrical activity in sheep
Author(s) -
BRIKAS P.
Publication year - 1989
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1111/j.1365-2885.1989.tb00669.x
Subject(s) - yohimbine , prazosin , phenylephrine , medicine , endocrinology , chemistry , alpha (finance) , propranolol , tolazoline , atenolol , receptor , antagonist , blood pressure , construct validity , nursing , patient satisfaction
In five conscious adult ewes at rest, chronically implanted with electrodes in the musculature of the omasal wall, intravenous (i.v.) infusion for 30 min of α 1 ‐ or α 2 ‐adrenergic receptor blockers, prazosin (20 μg/kg/min) and yohimbine (30 μg/kg/min), respectively, had no significant effects on omasal myoelectrical activity. The i.v. administration for 15 min of α 1 ‐ or α 2 ‐agonists phenylephrine (4 μg/kg/min) or naphazoline (2.5 μg/kg/min), respectively, increased the frequency and the amplitude of groups of myoelectrical discharges of omasum, as well as the duration of its activity. Pretreatment of animals with prazosin blocked the responses to phenylephrine. Yohimbine prevented the effects of naphazoline dose‐dependently. It is suggested that both α 1 ‐ and α 2 ‐adreno‐receptors are involved in regulation of the sheep's omasal notility. This regulation did not seem to be a simple consequence of the changes in the reticular motility.