Kinetic Analysis of the Clotting System in the Presence of Heparin and Depolymerized Heparin

Abstract

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(l), 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 Ila, which is accelerated by the anticoagulant. In contrast, the pattern of K(2)/K(l) 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(l) or its equivalent, the clotting time.

Blood plasma coagulation studied by surface plasmon resonance

“…It was observed that the plot of k value versus lag time overlapped for samples with and without heparin ͑not shown͒, indicating that the clotting process follows the same kinetics whether it is accelerated by thromboplastin or delayed by heparin. This is in contradiction to the results presented by others, 9 stating that k is a parameter more sensitive to the clotting kinetics than the lag time. The role of the detection method and the fitting equation needs to be investigated further.…”

Properties of Optical Data from Activated Partial Thromboplastin Time and Prothrombin Time Assays

“…Some variations of the PT assay also use the amplitude of signal change during coagulation to estimate fibrinogen concentration (z).Recent studies have attempted to identify ways in which additional information might be extracted from PT and AP[T, using parameters including the rate of coagulation (3,4). For example, we have described a method in which optical data for APTT and PT assays were charactenzedby a set…”