[Structural organization of the acellular region of the sinoauricular nerve plexus in the dog heart at maximal motor activity].

The reactions of the dog sinoatrial node artery under hypo- and hyperkinesia were revealed by the serial semi-thin section morphometric analysis. Single maximal physical load may be a cause of significant changes in the main source of blood supply of the dog heart sinoauricular region. During 4 weeks period hypokinezia leads to decrease of structural and functional reserve of the artery. The following physical load causes acute reduction of the blood volume in the region of the right atrium of the heart. The individual peculiarities of the artery adaptive reactions are determined by the level of the heart functional activity and by the cardiac muscle metabolism, which should be taken into account when using maximal physical loads in clinic and in experimental studies.