Comparison of the behaviour <i>in vivo</i> of two molecular forms of antithrombin III

Carlson, Timothy H.; Atencio, A C; Simon, Thomas

doi:10.1042/bj2250557

Cited by 29 publications

(11 citation statements)

References 18 publications

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“…The fact that thrombin inhibition was incomplete in 30 s also facilitated comparison of relative catalytic effects of low doses of glycosaminoglycans. Two complexes of human thrombin with both rabbit antithrombin III and heparin cofactor II were detected when the thrombin was added to rabbit plasma containing a variety of glycosaminoglycans; a finding consistent with previous observations (18,19).As shown in Figures 6 and 7, these complexes of thrombin with heparin cofactor II were sufficiently separated from those of thrombin with antithrombin III after electrophoresis to permit their quantitation.…”

Section: Discussionsupporting

confidence: 89%

Catalysis of Thrombin Inhibition Provides an Index for Estimating the Antithrombotic Potential of Glycosaminoglycans in Rabbits

et al. 1987

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SummaryPrevious studies have demonstrated that standard anticoagulant tests are poor indices of the antithrombotic potential of glycosaminoglycans which are weak catalysts of the thrombinantithrombin III reaction. In this study we investigated whether the catalysis of thrombin inhibition by plasma could serve as a reliable index for assessing the antithrombotic effectiveness of glycosaminoglycans. Equal volumes of 125I-thrombin and control or test plasma were incubated for up to 10 min at 37° C. Inactivation of thrombin was then determined after 7.9% SDS-polyacrylamide gel electrophoresis and subsequent autoradiography. Increasing concentrations of heparin (>0.066 μg/mL or 0.01 USP units/mL) and dermatan sulfate (>0.1 μg/mL) could be readily demonstrated in undiluted plasma by enhanced formation of complexes of thrombin with antithrombin III and heparin cofactor II respectively. However, the detection of any catalytic effect of the two glycosaminoglycans decreased significantly with increasing plasma dilutions. When ex vivo plasmas obtained from rabbits that had been injected with the minimum dose of any one of seven glycosaminoglycans required to achieve their optimal antithrombotic effect were assessed for their ability to catalyse thrombin inhibition, there was approximately a 2-fold increase in the amount of thrombin inactivated 30 s after the thrombin had been added to the plasma. The enhanced inhibition of thrombin was achieved by catalysis of antithrombin III and/or heparin cofactor II activities. These results suggest that measurement of the catalysis of thrombin inactivation in undiluted plasma is a sensitive and reliable index for estimating the antithrombotic potential of glycosaminoglycans in rabbits.

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Section: Discussionsupporting

confidence: 89%

Catalysis of Thrombin Inhibition Provides an Index for Estimating the Antithrombotic Potential of Glycosaminoglycans in Rabbits

et al. 1987

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“…Carlson et al 27 reported and we 29 have confirmed that the fractional catabolic rate of rabbit ATIII-£ in the vascular compartment and its fractional distribution in the extravascular compartment in the rabbit are substantially greater than corresponding values for ATIII-a. We infer from the comparative behavior of the isoforms in vivo and from the effects of thrombin in vitro (Figures 2 and 6) that the subendothelium-bound /3 isoform reacts more readily than a with thrombin on or within the vascular wall.…”

supporting

confidence: 66%

Antithrombin III-beta associates more readily than antithrombin III-alpha with uninjured and de-endothelialized aortic wall in vitro and in vivo.

Witmer

Hatton

1991

Arterioscler Thromb

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The properties of two isoforms, or and fi, of rabbit antithrombin III (ATIII) were compared in the presence of undamaged or de-endothelialized rabbit aortic wall. Similar quantities of ATIII-tt and ATUI-fi bound to and rapidly saturated the endothelium in vitro, but the rate of transendothelial passage of ATIII-/3 exceeded that of ATIII-a by 22%. Furthermore, ATIII-0 was adsorbed approximately twice as rapidly as ATlII-a by the subendothelium of the de-endothelialized aorta. Binding of both isoforms was decreased (ATIII-/3 more than Al'lU-or) by pretreating the subendothelial surface with heparitinase. Also, subendothelium-bound ATIII-/J was desorbed more readily than bound ATlII-aby thrombin. In vivo, the rate of uptake of iodine-131-labeled ATI1I-/3 from the circulation by the aortic wall and the major organs was 30-50% faster than that of iodine-125-labeled ATIII-o: In contrast, the uptake of m I-ATIII-0 by the de-endothelialized aorta in vivo was three times faster than that of '"I-ATlII-a. By these criteria, ATIII-^ is the more active of the two isoforms. We surmise that plasma and, consequently, vessel wall levels of ATIII-/3 may be vital for controlling thrombogenic events caused by injury to the vascular wall. (Arteriosclerosis and Thrombosis 1991;ll:530-539) F rom recent reports, two forms of the glycoprotein antithrombin III (ATIII) have been isolated from rabbit 1 and human 2 plasma. Both the rabbit and human isoforms were separated by gradient elution from a heparin-Sepharose affinity column, the major human isoform, ATIII-a, eluting at 0.9-1.0 M NaCl, and the minor isoform, ATIII-ft at 1.4 M NaCl.2 Human ATIII-0 was shown to contain approximately 25-30% less carbohydrate than ATIII-a.2 More recently, Brennan et al 3 have reported that, unlike the human ATIII-a isoform, which has four biantennary /V-glycans (at asparagine [Asn] 96, 135, 155, and 172), the ATIII-0 isoform possesses only three 7V-glycans, lacking that at Asn 135. Can-ell et al 4 have suggested that the absence of the N-glycan at Asn 135 may extend the binding site for heparin and, consequently, increase the affinity of ATIII-/3 for heparin.

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“…In that study, the authors deduced that a substantial proportion of antithrombin was contained in association with the vascular wall, a conclusion that others have since verified using other approaches (11,20,31). We have also studied the in vivo behaviors of the ␣and ␤-glycoforms of rabbit antithrombin (30) and found good agreement with the results previously reported for the rabbit antithrombin glycoforms (4). In addition, we have used the same three-compartment method to compare the in vivo behaviors of antithrombin and prothrombin in the rabbit circulation (13).…”

Section: Discussionsupporting

confidence: 87%

Metabolism of rabbit plasma-derived factor VII in relation to prothrombin in rabbits

Hatton

Blajchman

Sridhara

et al. 2001

American Journal of Physiology-Endocrinology and Metabolism

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In the human circulation, factor VII is present in relatively low plasma concentration (0.01 microM) and has been reported to have a short half-life (t(1/2); 6 h). In contrast, prothrombin is present in a relatively high plasma concentration (2 microM) and has a relatively long catabolic half-life (t(1/2) = approximately 2-3 days). This report examines the metabolic characteristics of purified rabbit plasma factor VII and prothrombin, radiolabeled with (125)I and (131)I, respectively, in healthy young rabbits. From the plasma clearance curves of protein-bound radioactivities, fractional catabolic rates and compartmental distributions were calculated using a three-compartment model. Turnover of factor VII within the intravascular space (2.95 days) exceeded that of prothrombin (1.9 days). However, the whole body fractional catabolic rate of factor VII (0.34 days(-1); catabolic t(1/2) = 2.04 days) was significantly slower than that of prothrombin (0.53 days(-1); t(1/2) = 1.31 days). Furthermore, the fractional distributions of factor VII in the intravascular (0.14) and extravascular compartments (0.76) differed from those of prothrombin (0.29 and 0.53). Absolute quantities of factor VII and prothrombin catabolized by a 3-kg rabbit amounted to 0.18 and 24.0 mg/day, respectively (molar ratio of prothrombin to factor VII = 100). The molar ratio of catabolism was compared with the release rates of factor VII and prothrombin from rabbit livers perfused ex vivo. After correction for uptake of factor VII and prothrombin by the liver, the molar ratio of released prothrombin to factor VII in the perfusate was approximately 293:1 over a 0.25- to 3-h interval. These results indicate that, compared with prothrombin, factor VII in the healthy rabbit circulates as a relatively long-lived protein. This behavior does not reflect that reported for factor VII in the human circulation.

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Comparison of the behaviour in vivo of two molecular forms of antithrombin III

Cited by 29 publications

References 18 publications

Catalysis of Thrombin Inhibition Provides an Index for Estimating the Antithrombotic Potential of Glycosaminoglycans in Rabbits

Catalysis of Thrombin Inhibition Provides an Index for Estimating the Antithrombotic Potential of Glycosaminoglycans in Rabbits

Antithrombin III-beta associates more readily than antithrombin III-alpha with uninjured and de-endothelialized aortic wall in vitro and in vivo.

Metabolism of rabbit plasma-derived factor VII in relation to prothrombin in rabbits

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