Observations on adrenergic innervation of dog heart

Abstract

The adrenergic innervation of the dog heart was studied by a histochemical fluorescence technique. The SA and AV nodes are extensively innervated by adrenergic fibers. Certain parts of the atria, auricles, and ventricles show a rich adrenergic innervation, while other parts of the same tissues are very deficient, suggesting that the sympathetic innervation to the heart is "patchy." The adrenergic innervation of the Purkinje cells is likewise very sparse, large numbers of cells showing no adrenergic innervation at all. It is suggested that the adrenergically innervated Purkinje cells exhibit a form of "pacemaker" activity.