[Effect of longitudinal gravitational loads on the structure of the wall of the vertebral artery].

A single exposure to the greatest endurable gravitation stress causes such changes in the wall of the vertebral artery as division into layers, oedema, vacuolization of smooth muscle cells. Repeated exposure according to a training schedule resulted in reconstruction of the vascular wall (division of the medial sheath of the artery into several muscular layers). Concentration of smooth muscle cells in "layers" increased when training was after a "cumulative" schedule. Under conditions of increasing cumulative effect the collagenization of the media and dystrophy of the muscular and elastic tissue began. The greatest changes in the arterial wall took place in the upper parts of the vertebral artery at the level of the 2nd and 3d cervical vertebra.