Necrosis of aorta, myocardium and brain in rabbits following orthostatic shock: main aortic involvement

A microscopical examination of aorta, myocardium and brain of 10 New Zealand White male rabbits submitted to orthostatic shock was performed. In addition six normal animals were used as controls. Seven animals were sacrificed 24 hours following shock by perfusion fixation and three animals three and half to seven hours thereafter. Necrotic changes were present and severe in aortic media, mild in myocardium and minimal in brain neurons. The great difference of involvement of these organs may be related to less vascularization of aortic media as compared with myocardium and brain, and presence of autoregulatory mechanisms of circulation during shock in myocardium and brain. Severe degenerative alterations of aortic media often leading to tissue necrosis due to shock is of importance for the pathogenesis of dissecting aneurysms and experimental atherosclerosis.