[Relationship of inotropic vagal effects to stretching of the atrium].

Isolated left rabbit atria were tested. Preparations are vagal innervated and driven by a constant frequency. Isovolumetric contractions, volumes of the auricles and intraatrial pressures were recorded. With increasing intraatrial pressure the effectivity of peripheral nerve-ending stimulation decreases. There exists a critical value of atrial area. The vagal effectivity will decrease rapidly, if the atrial surface increases higher than this critical value by stretching the auricles.