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A DEPRESSANT EFFECT OF ACETYLCHOLINE ON THE IDIO‐VENTRICULAR PACEMAKER OF THE ISOLATED PERFUSED RABBIT HEART
Author(s) -
BENFORADO J. M.
Publication year - 1958
Publication title -
british journal of pharmacology and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0366-0826
DOI - 10.1111/j.1476-5381.1958.tb00231.x
Subject(s) - depressant , acetylcholine , rabbit (cipher) , pharmacology , physostigmine , medicine , anesthesia , chemistry , statistics , mathematics
In Langendorff preparations of the isolated rabbit heart, excision of the atria and severance of the atrio‐ventricular bundle resulted in the onset of idio‐ventricular rhythm at a rate much below the original sino‐atrial rate. The mean decrease in rate in twelve experiments was 61%. Acetylcholine perfusion decreased the idio‐ventricular rate still further. Physostigmine augmented this effect while atropine prevented or abolished it. Similar results were obtained with a rat heart. The results indicate that a cholinergic receptor mechanism is present at pacemaker sites in mammalian ventricles. However, when rabbit ventricles, beating under atrio‐ventricular nodal rhythm or idio‐ventricular rhythm, were cooled to the point of cardiac arrest, acetylcholine failed to cause reappearance of the cardiac beat.