Key anatomic data for the use of rat heart in electrophysiological studies of the intracardiac nervous system.

The aim of the present study was to elucidate both the topography and architecture of the rat intrinsic cardiac nerve plexus, as this species becomes a frequent mammalian model for electrophysiological investigations of the intracardiac nervous system. Fifteen adult rats were examined employing histochemistry for acetylcholinesterase to visualize the intracardiac nerve plexus in hearts. Extracardiac nerves entering the rat heart were found amid aorta and pulmonary trunk as well as along both right and left cranial veins. The nerves from the arterial part of the heart hilum extended directly to the ventricles but the nerves from the venous part of the hilum interconnected among themselves forming a nerve plexus of the cardiac hilum on the heart base. Within the rat epicardium, intrinsic nerves clustered into six routes by which they selectively projected to different rat heart regions. Ventral wall of the ventricles was supplied by three neural subplexuses, dorsal ventricular wall--by one subplexus; each atrium received nerves from two distinct subplexuses. In conclusion, this morphological study demonstrates that rat intracardiac nerve plexus compounds to anatomical scheme of the same plexus in human, therefore rat is a usable model for electrophysiological experiments of the intracardiac nervous system.