Changes in the morphology and components of the coronary arteries during the progression of coronary arteriosclerosis following cardiac transplantation in rats

Abstract

In order to examine the changes in coronary artery morphology following cardiac transplantation, the intimal and medial areas and vascular components were measured 30 and 60 days postoperatively in rats receiving both iso- ( n=5, each time) and allotransplantations ( n=7, each time). Although cyclosporine A was administered intramuscularly (10 mg/kg per day) for 20 days following transplantation, graft rejection progressed gradually in the allotransplanted group. There were no clear changes in the intimal or medial areas following transplantation in the isotransplanted group. The intimal area of the coronary arteries in the allograft group was significantly thicker 30 and 60 days following transplantation, while the medial area of the coronary arteries in this group was significantly thinner than that of the isotransplantation group at these same time points. In the thickened intimal areas in the allotransplantation group, only the density of smooth muscle cells was higher following transplantation. In the thinned medial areas in the allotransplantation group, the densities of the smooth muscle cells and collagen were less than those in the isotransplantation group. These changes suggest that following transplantation, smooth muscle cells proliferate in the intimal areas, while smooth muscle cells and collagen are degraded in the medial areas.