Histopathological reactivity of carotid arteries of normotensive Sprague-Dawley vs spontaneously hypertensive rats to ligation injury.

The common carotid arteries of normotensive non-arteriosclerotic Sprague-Dawley (S-D) rats, mildly hypertensive but arteriosclerotic breeder S-D rats, severely hypertensive but non-arteriosclerotic virgin spontaneously hypertensive rats (SHR), and severely hypertensive breeder SHR were ligated to induce injury. Three weeks post-ligation, the animals were killed and histopathological sections of the ligated artery demonstrated myointimal proliferation without occlusion in the normotensive S-D rats but myointimal proliferation with occlusion in the severely hypertensive SHR. Breeder S-D rats with moderate hypertension manifested a high incidence of total occlusion by combined myointimal proliferation and thrombosis. Severely hypertensive breeder SHR manifested a high incidence of massive thrombi containing cholesterol clefts causing total occlusion of the injured artery. It is suggested that the severity of the hypertension and the hormonal-metabolic milieu conditions the morphologic response of the arterial wall to injury.