Abstract
Leak of lysosomal enzymes is a possible indicator of permeability of the cell membrane. Acceleration of such permeability in diabetics may cause diabetic microangiopathy. Elastase is one of the lysosomal and collagen-hydrolytic enzymes. The activity of elastase in plasma and granulocytes of diabetics was measured by the method of Katagiri using succinyl-trialanine-p-nitroanilide. Results are presented as the mean±SD.
The enzyme activity in the plasma of diabetics (0.073±0.018/h) was significantly (p<0.001) greater than that in the plasma of non-diabetics (0.062±0.012/h). The enzyme activity in the plasma of diabetics was 0.068±0.020/h for the diet group, 0.071±0.014/h for the group treated with oral hypoglycemic agents and 0.080±0.016/h for the insulin group. There were significant differences between the enzyme activity of plasma in non-diabetics and that in plasma of the group treated with oral hypoglycemic agents (p<0.05), and between the enzyme activity in plasma of non-diabetics and that in plasma of the insulin group (p<0.001).
The enzyme activity in the plasma of diabetics with proteinuria (0.082±0.015/h) was significantly (p<0.01) greater than that in the plasma of diabetics without proteinuria (0.068±0.017/h). There was no significant difference between the enzyme activity in the plasma of diabetics with and without retinopathy. There was no significant correlation between the activity in the plasma of diabetics and HbA1c.
Granulocytes obtained from the patients were destroyed by supersonic waves, followed by centrifugation. The supernatant was used an enzyme solution. Protein content in the enzyme solution was measured by the method of Lowry. The level of enzyme activity in the granulocytes was expressed as absorbance value/h/pg protein. The levels of enzyme activity in the granulocytes of diabetics (4.68×10-3±1.85±10-3/h/μg protein) were significantly (p<0.05) less than the enzyme activity in the granulocytes of non-diabetics (5.56×10-3±1.76×10-3/h/μg protein). There was no significant difference between or among the levels of enzyme activity in the granulocytes of diabetic groups classified according to the types of therapy given the presence of proteinuria and the presence or grade of retinopathy.
Previosuly we observed that enzyme activity in the kidney cortices of streptozotocin-treated diabetic rats was significantly less than that in the kidney cortices of control rats. The enzyme activity in the plasma of diabetic rats was significantly greater than that in the plasma of control rats.
It may be that the activity of elastase as a collagen-hydrolytic enzyme in the glomerulus of diabetics is low. Such a low content of elastase activity in the glomerulus leads to thickness of the basement membrane and subsequent diabetic glomerulosclerosis.
