PERIARTERITIS NODOSA IN SPONTANEOUSLY HYPERTENSIVE RATS

Abstract

Male SHR rats from Nihon rat Inc. developed spontaneously periarteritis nodosa with high incidence. Macroscopically, periarteritis nodosa was obvious in the mesenteric arteries as bead‐like or lead‐pipe‐like appearance. Microscopically, the lesion was compatible with Abrinoid arteritis and similar to that of human periarteritis nodosa. On the morphological basis, the preceding changes of the artery might be regarded as the medial damage especially of smooth muscle cells. The medial smooth muscle cells underwent degenerative changes and disappeared with an increase in basement‐membrane‐like substance and then the blood plasma and plasma proteins insudated into the subendothelial space frequently with leukocytic inflltration, and resulted in full‐blown Abrinoid arteritis. The initial changes, however, were subdivided into two types according to the arterial size involved. In the large‐sized arteries, leukocytic inflltration or fibrinous insudation without rupture of the internal elastic membrane was frequently observed. In the small‐sized arteries, insudation of blood plasma and dissolution of the internal elastic membrane occurred simultaneously.