Abstract

Since fibrinolytic potential has been reported to be enhanced in the alloxan-induced hyperglycemic rat it was of interest to determine the response of the fibrinolysin system to the induction of a hypoglycemic state. Animal experiments were designed to study the alterations in the fibrinolysin system as a result of insulin-induced hypoglycemia in rats. Insulin, at a dose of 5 units/kg s.c. administered once, produced a significant hypoglycemia. Significant changes in the fibrinolysin system 4 hours later included: a decrease in euglobulin clot lysis activity, increased acid-labile inhibitors of plasmin on unheated and heated fibrin plates and increased plasma fibrinogen. Eight hours after insulin the euglobulin clot lysis activity was significantly reduced while the acid-labile inhibitors of plasmin and plasminogen activation were increased. Twenty-four hours after insulin the plasma glucose levels were significantly elevated as were the acid-labile inhibitors of plasmin and plasminogen activation and the plasma fibrinogen levels. During the 24-hour period after insulin the plasminogen and fast and slow antiplasmin levels did not change. The overall suppression of fibrinolytic activity was due to the increase in the acid-labile inhibitors of plasmin and plasminogen activation. The rat with its fibrinolysin system suppressed by insulin can be adopted as an experimental model for the study of the ability of nonenzymatic pharmacologic agents to enhance or induce fibrinolytic activity.