Collagen metabolism in syngeneic aortal vein grafts in the rat

The sequential changes in hydroxyproline concentration and in vivo 3H-proline incorporation in arterialized grafts of the supradiaphragmatic inferior vena cava have been studied. These grafts were transplanted from one rat to the abdominal aorta of another rat of the same inbred strain, i.e., syngeneic grafts. The hydroxyproline (collagen) concentration decreased to half of its pregraft value one week after the transplantation and thereafter increased again, reaching its peak value 4 weeks after transplantation. The pregraft level of collagen concentration was not reached within the observation period of 12 weeks., The incorporation of 3H-proline increased and reached its peak value one week after transplantation. The values then levelled off and one month after the transplantation were slightly elevated. These results indicate that the reduction of collagen concentration after grafting was due to an increased breakdown, which was compensated by increased collagen synthesis. This probably signifies that the collagen in the vein wall is remodelled as a response to the altered hemodynamic milieu following its insertion to the arterial circulation. The collagen concentration did not reach pregraft level. This is most likely due to a relative increase of ground substance, smooth muscle cells and elastin in the vein wall.