Abstract
Thrombomodulin (TM) is known to exist in the glomerulus and to be excreted in urine. To elucidate biochemical properties of urinary TM in normal and toxemic pregnancy, the levels of immunoreactive TM (TM antigen) and its activities were measured by ELISA and by a protein C activation method, respectively. The samples for measurements were prapered from urine by DIP-thrombin agarose affinity chromatography.
The urinary protein fraction bound to DIP-thrombin agarose, obtained from normal pregnants, pregnants with early onsets type toxemia (24-28 weeks of gestation), and with late onset type toxemia (later than 32 weeks) commonly showed a single band with a mol. wt. 63Kd in SDS-polyacrylamide gel electrophoresis with silver staining.
The levels of urinary TM antigen and TM activity in normal pregnancy increased with gestation weeks. Those in late onset type pregnancy showed similar chnges. There was no difference in the ratio of TM activity/antigen between these two types of pregnancy. However, in early onset type toxemia the level of TM activity was low, and, further, the ratio of TM activity/antigen was extremely low.
The TM in early onset type toxemia had a significantly lower Vmax than that in normal pregnancy. These findings suggested that the TM in early onset type toxemia was functionally impaired as a cofactor for thrombin.
