title: Recombinant Kunitz protease inhibitory domain of the amyloid beta-protein precursor as an anticoagulant in venovenous extracorporeal circulation in rabbits.
abstract: Investigations were performed to characterize a recombinant Kunitz protease inhibitory domain of the amyloid beta-protein precursor (rKPI) as anticoagulants. After a single intravenous infusion of wild type rKPI into dogs, its elimination fit a two compartment model with a t1/2alpha and t1/2beta of 5 and 77 min, respectively. Further investigations determined if a variant form of rKPI with 178-fold more potent anti-factor Xa activity (rKPI-DD135, Ki = 0.9 nM) could serve as an anticoagulant in a rabbit model of extracorporeal circulation using a venovenous shunt. A prospective investigation was initiated to compare standard heparin (n = 8) at 400 U/kg with different infusion concentrations of rKPI-DD135. After a single intravenous infusion of 1.89 mg/kg of rKPI-DD135 followed by a constant infusion at 0.003 (n = 3), 0.03 (n = 7), or 0.3 (n = 5) mg/kg/min, the anti-factor Xa activity of the animals' plasma rapidly reaches a steady state for the two lower infusion concentrations of the agent. All infusions of rKPI-DD135 prolong the activated clotting time with less variation than that seen with heparin administration. rKPI-DD135 anticoagulation does not prevent a drop in the platelet counts. Fibrinogen levels decrease only slightly when the circuit is anticoagulated with rKPI-DD135. rKPI-DD135 markedly prolongs the APTT, has little effect on the PT, and reduces plasma prekallikrein and plasminogen activation. The 0.3 mg/kg/min infusion concentration of rKPI-DD135 results in reduced deposition of 111Indium-labeled platelets on the circuit when compared to heparin. Last, after a steady state level is achieved, 60% of the plasma anti-factor Xa activity of rKPI-DD135 is eliminated within 60 min after stopping the infusion. These data show the rKPI-DD135 can provide single agent anticoagulation in a rabbit extracorporeal circuit. Development of short acting factor Xa inhibitors may be useful anticoagulants for cardiopulmonary bypass.
authors.affiliation: Department of Pediatrics, University of Michigan, Ann Arbor 48109-0640, USA.
authors.forename: G
authors.initials: G
authors.lastname: Annich
authors.forename: T
authors.initials: T
authors.lastname: White
authors.forename: D
authors.initials: D
authors.lastname: Damm
authors.forename: Y
authors.initials: Y
authors.lastname: Zhao
authors.forename: F
authors.initials: F
authors.lastname: Mahdi
authors.forename: J
authors.initials: J
authors.lastname: Meinhardt
authors.forename: S
authors.initials: S
authors.lastname: Rebello
authors.forename: B
authors.initials: B
authors.lastname: Lucchesi
authors.forename: R H
authors.initials: RH
authors.lastname: Bartlett
authors.forename: A H
authors.initials: AH
authors.lastname: Schmaier
mesh_terms: D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D000818:Animals; D000925:Anticoagulants / Q000493:pharmacokinetics / Q000494:pharmacology*; D001777:Blood Coagulation / Q000187:drug effects*; D004285:Dogs; D005112:Extracorporeal Circulation; D065427:Factor Xa Inhibitors; D005340:Fibrinogen / Q000032:analysis; D006439:Hemodynamics; D010446:Peptide Fragments / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology*; D010958:Plasminogen / Q000032:analysis; D011288:Prekallikrein / Q000032:analysis; D017434:Protein Structure, Tertiary; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D016564:Amyloid beta-Protein Precursor; D000925:Anticoagulants; D065427:Factor Xa Inhibitors; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; D005340:Fibrinogen; D010958:Plasminogen; D011288:Prekallikrein