Heart rate (HR) in freely moving rats was determined by means of original non-invasive phonocardiography registration technology. HR was determined during food-obtaining movement with 10 s epoch of analysis after development of instrumental reflex. Bradycardia phenomenon for 3–4 s during food-procuring movements was established. A supposed vagus mechanism was excluded by introduction of atropine. Bradycardia phenomenon was re-registered during realization of food-obtaining movements at the background of atropine tachycardia (HR=480–520 s-1). Inhibition of sympathetic heart innervation as possible mechanism of short-time decrease of HR at the background of atropine tachycardia is discussed.
