Congruence of adrenergic and cholinergic intrinsic innervation of human and rat atria.

Right atrial biopsies from rat and human hearts were studied using combined methods for the demonstration of glyoxylic acid-induced fluorescence (GIF) of catecholamines and acetylcholinesterase (AChE) reactions in the same specimens. In specimens from the rat heart, the GIF and AChE reactions were performed either simultaneously or consecutively. In biopsies of the human right atrium, obtained at right atria cannulation during open-heart surgery, the reactions were performed consecutively. It was found that in both rat and human atria the adrenergic nerves and AChE reactive nerves, which are probably cholinergic, run partly separately and partly together. In the rat atrial specimens, close relations between adrenergic nerves and clusters of AChE reactive cells were observed. In addition, clusters of fluorescent cells were observed in the vicinity of AChE reactive nerve bundles. This indicates that there may be several possible means of peripheral interaction between the intrinsic adrenergic and cholinergic systems of the rat heart.