Neutralization of DHG, a New Depolymerized Holothurian Glycosaminoglycan, by Protamine Sulfate and Platelet Factor 4

Abstract

The neutralization of depolymerized holothurian glycosaminoglycan (DHG), unfractionated heparin (UFH), and low-molecular-weight heparin (LMWH) by protamine sulfate (PS) or platelet factor 4 (PF4) was studied. In in vitro studies, the prolongation of thrombin clotting time (TCT) by these glycos-aminoglycans was completely neutralized by PS, whereas activated partial thromboplastin time (APTT) was relatively resistant to neutralization. In rats, prolongation of bleeding time by DHG was neutralized by PS with concomitant normalization of TCT ex vivo. Heparin-cofactor-II-dependent antithrombin activity of DHG or UFH was neutralized by PF4 at a high concentration to the same extent; however, prolongation of the APTT by DHG was more resistant to neutralization by PF4 at a physiological plasma level than that by UFH. In conclusion, since the prolongation of bleeding time by DHG was neutralized by PS with concomitant normalization of TCT, and since PF4 neutralized the antithrombin activity of DHG, these proteins may be useful as antidotes for DHG to prevent bleeding in case of an overdose.

Holothurian Fucosylated Chondroitin Sulfate

“…Similar to the clinical procedure of UFH neutralization routinely done in heparin-treated patients, the action for stopping the DHG anticoagulant activity was also studied using the proteins protamine sulfate and PF4 [35]. Given that the prolongation of bleeding time by DHG can be completely neutralized by protamine sulfate with concomitant normalization of TCT, and because thrombin inhibition activity of DHG can be neutralized by PF4, these two proteins can be safely used as antidotes for DHG to prevent the bleeding effect in case of an overdose [35].…”

“…Given that the prolongation of bleeding time by DHG can be completely neutralized by protamine sulfate with concomitant normalization of TCT, and because thrombin inhibition activity of DHG can be neutralized by PF4, these two proteins can be safely used as antidotes for DHG to prevent the bleeding effect in case of an overdose [35]. …”