Inhibition by Low Molecular Weight Dextran of the Blood Pressure Fall and the Lowering of Plasminogen Proactivator Induced by Clinical Dextran in the Rat

: The intravenous injection into rats of dextran with a molecular weight of 1,000 (LMr dextran) in doses 200 mg/kg induced rapid, but transient falls in blood pressure. Pretreatment of the rats with LMr dextran 200 mg/kg caused a partial inhibition of the profound blood pressure fall induced by the injection of clinical dextran with a molecular weight of 70,000 (HMr dextran), 40 mg/kg. In accordance with previous works (Briseid & Berstad 1981; Berstad & Briseid 1982; Berstad 1982) it was found that the intravenous injection of HMr dextran lowered the plasma levels of plasminogen proactivator (pro‐PGA) and functionally active high molecular weight kininogen (HMrK). Also LMr dextran, 200 mg/kg, induced significant reductions in the mentioned parameters, but less extensive than those obtained by HMr dextran, 40 mg/kg, and pretreatment of the rats with LMr dextran inhibited the subsequent effects of HMr dextran. It is suggested that a dextran‐activated plasminogen activator might be an early link in the mechanism underlying the dextran‐induced state of shock in the rat.