“Experimental arteriosclerosis”

Abstract

Within the past two years several French and German writers (Josué, Erb and others) have described under the various names of calcification, atheroma or arteriosclerosis, a lesion of the aorta of rabbits produced by the intravenous injection of adrenalin. These experiments have been repeated for the purpose of making detailed histological studies and in the hope of throwing some light upon the histogenesis of arteriosclerosis in man.

Methods.—Rabbits have received injections of a 1 to 1,000 solution of adrenalin in the ear vein. An initial dose of 3 m. repeated every other day has been the usual procedure. In other instances, the dose has been gradually raised until a dose of 20 m. to 25 m. was given every day. The animals have been killed after periods varying from a few days to eight weeks.

Results.—The vascular lesions produced are limited to the aorta and exhibit a more or less definite sequence. Rabbits receiving five to six injections show no gross lesions, but histologically important changes in the media are evident. These consist of focal areas of degeneration in which the muscle fibers are destroyed without alteration of the elastica. Later the degeneration is more extensive and involves the greater portion of the middle zone of the media. At this time changes in the elastic tissue appear; the fibers become swollen, stain irregularly and in some places appear to be fused together. Special stains show a small number of minute fat droplets in such areas. After twelve to fifteen injections very definite lesions are evident macroscopically. The aorta is more or less distorted, rigid and nonelastic. Irregular dilations alternate with elevated brittle areas of calcification. Distinct atheroma with ulceration is seldom seen. In the experiments continued for six to eight weeks, the process becomes very diffuse and small dilations of the thinner portions of the aorta assume the appearance of aneurysms.