Comparison between commercial heparin, low molecular weight heparin and pentosan polysulfate on hemostasis and platelets in vivo.

The effect of commercial heparin (MW 15000; 60 U/kg), low molecular weight heparin (MW 4500, 60 U/kg), sodium pentosan polysulfate (PZ-68) in doses of 0.5, 1, 2 and 5 mg/kg and 1 mg/kg combined with dextran 70 (0.5 g/kg) on microvascular hemostasis and platelet activity in vivo was investigated in the microcirculation of rabbit mesentery and ear chamber, respectively. Low molecular weight heparin did not alter the hemostasis: nonetheless, commercial heparin and PZ-68 interfered with the hemostatic mechanism by decreasing the stability of the hemostatic plug. This abnormality was more apparent in the venular than in the arteriolar system. Both heparins exhibited a trend towards an increase in platelet reactivity and the reverse was observed following the administration of PZ-68.