Elastase-type activity in human radial artery in patients with chronic renal failure

To elucidate the nature of the abnormality of elastin metabolism in arteriosclerosis, we determined the elastase-type activity in the human radial artery of patients with chronic renal failure due to glomerular disease and diabetes. Elastase-type activity was determined by HPLC analysis of the hydrolyzed products of succinyl-trialanine-4-nitroanilide, a sensitive synthetic substrate for elastase. Three kinds of hydrolyzed products, (L-Ala)2-NA, L-Ala-NA and NA, were found after incubation of the substrate with human radial artery in the presence of amastatin (an inhibitor of aminopeptidases). We assumed the activity that liberates NA to be an elastase-type activity because purified human aorta elastase liberates NA from the substrate. The pH optima of the human artery and rat aorta activities were 6.0 and 6.8, respectively. The elastase activity in human radial artery and rat aorta was inhibited by diisopropyl phosphofluoridate, a serine protease inhibitor, and by elastatinal, an elastase inhibitor. The elastase-type activity in the radial artery of patients with chronic renal failure was significantly lower than that of the control group, and the decrease was especially marked in the patients with juvenile onset diabetes. These results suggest that the elastin metabolism is abnormal in the radial artery in diseases that tend to cause atherosclerosis.