Plasminogen activation in diabetes mellitus. Kinetics of plasmin formation with tissue plasminogen activator and plasminogen from individual diabetic donors and with in vitro glucosylated plasminogen.

Functional abnormalities of tissue plasminogen activator (t-PA) (high Km in the presence of fibrin) and plasminogen (Pg) (substrate inhibition in the fibrin-stimulated system) from uncontrolled type I diabetics are reversible upon normalization of metabolic parameters. Therefore the effect of in vitro glucosylation of Pg was studied and similar but less pronounced substrate inhibition as with diabetic Pg was observed. However, the activation of the Pg fraction most likely containing bound cis-OH groups (e.g. glucose) was normal. These data suggest that either glucosylation in vitro is less stable than in vivo or that in diabetics protein modifications other than glucosylation occur. In this respect we can also show that acetone, a representative of ketone bodies and also elevated in poorly controlled diabetics, does not affect Pg activation in vitro.