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“The action of sympathomimetic amines on the isolated heart of the frog”.
J Pharmacol Exp Ther. 1949 Aug 01;96(4 Pt. 1):365-71.
The frog's heart isolated according to the technique of Straub appears to be a satisfactory tissue for studying the relationship of structure of ‘sympathomimetic’ agents to their action on a functioning muscular tissue essentially free of active adrenergic nerve fibers. This preparation responds regularly by inotropic changes, whereas chronotropic actions are less constant, due to the absence of or poor perfusion of the pace-maker tissues. Hoffman ci al. 1 have shown that the isolated frog’s heart is free of active chromaffin tissue. They found that the atropinized frog’s heart does not respond to acetylcholine. The isolated atropinized hearts of mammals, however, are stimulated by acetylcholine and this stimulation is due to the release by acetylcholine of a sympathin-like substance.
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