The Wistar rat line hemostatic system characteristics to be important for experimental surgery.

Abstract

Background. Testing a new method of hemostasis in surgery often goes through the experimental stage. The key point is selecting animals, and eligibility of the obtained experimental results extrapolating to humans. Experimental rats are often used for studying the hemostasis system indicates in modeling various pathologies in surgery. The emergence of the low-frequency piezothromboelastography (LFPTEG) technique in combination with the coagulogram findings, general blood test, protein C, and plasminogen indicators has been able to detail the available knowledge about the hemostasis system originality at these animals and to help avoiding errors in interpreting the results obtained in the experiment.
 Aim. To determine the features of the Wistar line rats hemostasis system parameters in comparison with the same human ones being important for experimental surgery.
 Materials and methods. The research was conducted on Wistar male rats (n=32) weighing 349 ±33 g (M±σ). Blood was taken from the left carotid artery under conditions of anesthesia with tiletamine / zolazepam (20-40 mg / kg intramuscularly) + xylazine (5-10 mg / kg intramuscularly). Eight seconds before blood without citrate in a volume of 0.45 ml was placed in a cuvette of the LFPTEG technique ARP-01M “Mednord” in settings of which the delta was used to take a maximum point equal to 1, and the waiting time of the curve rising was 20 minutes. The next blood sample was collected in a test tube with 3.8% citrate in a volume of 4.5 ml (9:1) for investigating the fibrinogen level at the Thrombotimer 4 Behnk Elektronik semi-automatic coagulometer, the activated partial thromboplastin time (APTT) values, prothrombin time (PT), thrombin time (TT) and antithrombin III at the automatic blood coagulation analyzer Sysmex CA 600, and activity of plasminogen and protein C at the semi-automatic Riele 5010 v5 + photometer with a wave length of 405 nm. Studying the hematocrit indicators, and determining the platelet count were performed at the automatic hematological analyzer ABX Micros ES 60. The reagents of Ltd "Tekhnologiya standart" were used for detecting the parameters of the hemostasis system. Parameters of the LFPTEG technique for human had been taken from the cited literature, the other indicators had been obtained from 120 healthy adult volunteers. Statistical processing was implemented in the programming language R with using the statistical packages “VIM”, “mice”, “car”, “sm”, “coin”, “boot”. The LFPTEG technique reference values ​​ in rats were refined by the nonparametric bootstrap method. The comparison between the groups was carried out by Mann- Whitney's test and rechecked by the Permutation test with the level p correction for multiple comparisons by the Benjamin-Yekutili method. After correction the α level was assumed to be 0.05.
 Results and Discussion. Most indicators of the rat hemostasis system differed from the same human parameters, except the hematocrit (p3=0.84, p4=0.98) indicator, and the lysis intensity, and retraction of the clot (p3=0.15, p4=0.067) indices. The I-II coagulation phases were increased at the background of decreasing protein C activity by 29%, increasing the number of platelets and their activity by 69% and 79%, intensification of thrombin activity and acceleration of its formation by 35% and 30% in a rat compared to a person. At the III phase of coagulation the proteolytic stage was noted to become intensified by 37% and the polymerization to become weakened by 44%. The clotting time was shortened by 29%, and the thrombin time was prolonged by 64% that did not contradict the coefficient growth of total anticoagulant blood activity (TAAC) by 62%. Other indicators have clinically differed a little.
 Conclusion. The Wistar line rats haemostasis system is very similar to human one except significant increasing of the I-II coagulation phases, the III proteolytic phase, and significant weakening of its polymerization stage probably due to increasing the plasmin system activity, the anticoagulant blood activity at this stage, and decreasing the fibrinogen level. Rats evolutionarily must be considered to be better suited to stop bleeding after trauma while performing a surgical experiment.