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Kinetic analysis of the clotting system in the presence of heparin and depolymerized heparin
The kinetics of the activation of the plasmatic clotting system in the presence of heparin and depolymerized heparin (Kabi 2165), respectively, was compared with the kinetics of activation in plasma with isolated factor deficiency. Measurements were made with a chromogenic substrate method using Tos-Gly-Pro-Arg-p-nitroanilide acetate. The extinction curves were analyzed to determine the characteristics of a curve that was fitted to the experimental data to sufficiently describe the slope of the curves by constants. In the activated extrinsic clotting system, the action of heparin and depolymerized heparin results in a distribution pattern for the two relevant constants. K(1), defining the time of the point of inflection of the curve, and K(2), relating to the slope of the curve at the point of inflection, which is identical with the pattern observed in plasma with factor II deficiency. This distribution pattern can be explained by an inhibitory reaction on factor IIa, which is accelerated by the anticoagulant. In contrast, the pattern of K(2)/K(1) for the activated intrinsic system is identical with the pattern for plasma with factor X deficiency. Qualitative differences in the action of heparin and depolymerized heparin are not evident. The investigation confirms that the molecular action of heparin and depolymerized heparin as accelerators of the plasmatic clotting system is qualitatively the same. However, their action in the extrinsic and intrinsic system has different effects. Furthermore, the study reveals that constant K(2) is a more sensitive indicator to measure low heparin and depolymerized heparin activities than K(1) or its equivalent, the clotting time.
The kinetics of the activation of the plasmatic clotting system in the presence of heparin and depolymerized heparin (Kabi 2165), respectively, was compared with the kinetics of activation in plasma with isolated factor deficiency. Measurements were made with a chromogenic substrate method using Tos-Gly-Pro-Arg-p-nitroanilide acetate. The extinction curves were analyzed to determine the characteristics of a curve that was fitted to the experimental data to sufficiently describe the slope of the curves by constants. In the activated extrinsic clotting system, the action of heparin and depolymerized heparin results in a distribution pattern for the two relevant constants. K(1), defining the time of the point of inflection of the curve, and K(2), relating to the slope of the curve at the point of inflection, which is identical with the pattern observed in plasma with factor II deficiency. This distribution pattern can be explained by an inhibitory reaction on factor IIa, which is accelerated by the anticoagulant. In contrast, the pattern of K(2)/K(1) for the activated intrinsic system is identical with the pattern for plasma with factor X deficiency. Qualitative differences in the action of heparin and depolymerized heparin are not evident. The investigation confirms that the molecular action of heparin and depolymerized heparin as accelerators of the plasmatic clotting system is qualitatively the same. However, their action in the extrinsic and intrinsic system has different effects. Furthermore, the study reveals that constant K(2) is a more sensitive indicator to measure low heparin and depolymerized heparin activities than K(1) or its equivalent, the clotting time.