Physiological features of primary hemostasis in cows during pregnancy kept in the conditions of central Russia

Abstract

The functional parameters of blood vessels and platelets are of great biological importance throughout the life of the animal. Their activity is designed to provide the necessary level of rheological properties of blood in vessels of small and medium caliber. In the work carried out in cows during pregnancy, a decrease in the sensitivity of platelets to stimulators of platelet activity was revealed. This, apparently, leads them during pregnancy to curb adhesion and aggregation of platelets. A decrease in the hemostatic properties of platelets in cows during pregnancy is largely due to a weakening of the expression on their surface of receptors that can bind to aggregation inducers and fibrin, a decrease in thromboxane synthesis, inhibition of myosin formation and actin formation, a weakening of the secretory release of adenosine phosphates from platelet granules and a decrease in the level of activity in the blood cells. plates of phospholipases A2 and C. Strengthening in cows during pregnancy of the disaggregation properties of blood vessels is associated with an intensification of the synthesis in their walls of deaggregants of prostacyclin and nitric oxide, which enhance trophism in fetal tissues. Changes in the activity of primary hemostasis that develop in cows as pregnancy proceeds are associated with a decrease in the functional characteristics of platelets and an increase in the functionality of the vascular element of hemostasis, providing optimal conditions for capillary perfusion and active anabolism in the growing fetus.