Effects of the hormones of the thyroid axis on the vitamin K-dependent plasma factors of blood coagulation (II, VII, IX, and X).

The hormonal regulation of haemostasis is a problem which has not received much attention. The data concerning the influence of hormones from the hypothalamic-pituitary-thyroid axis are scarce, contradictory and based mainly on clinical observations. The objective of the current research is to study the influence of the Thyrotropin releasing hormone (TRH), Thyroid stimulating hormone (TSH), Triiodothyronine (T3) and Thyroxin (T4) on the activity level of the vitamin K-dependent plasma factors of blood coagulation--factor II (F II), factor VII (F VII), factor IX (F IX) and factor X (F X). This study was carried out on 40 male Wistar rats. The necessary quantity of blood was obtained by cardiac puncture under ether narcosis. The indicators studied were activated partial thromboplastin time (aPTT), protothrombin time (PT), F II, F VII, F IX and F X, and were determined by means of Diagnostica Stago tests and with the help of an automatic coagulometer. The hormones studied were: TRH (0.06 mg/kg b.w.), TSH (1 MU/kg b.w.), T3 (0.08 mg/kg b.w.) T4 (0.08 mg/kg b.w.) prolonged aPTT (p<0.001) and PT (p<0.001). TRH and T3 significantly reduced the activity level of factors II, VII, IX and X; T4 only reduced the level of F II (p<0.05), and TSH did not induce significant changes in the haemocoagulation factors studied. The TRH, TSH, T3 and T4 hormones, although elements of one and the same axis, have an ambiguous effect on the vitamin K-dependent factors of blood coagulation. The results obtained show that the determined changes in the activity levels of the vitamin K-dependent plasma factors of blood coagulation are undoubtedly related to the hypocoagulation observed in the intrinsic and extrinsic pathways under the influence of the hormones of the thyroid axis.

Screening study of the effects of the hypothalamic-pituitary-thyroid axis on hemostasis in rats.

The hormonal regulation of hemostasis has had little attention in research, and the existing literature data are relatively contradictory. The possible effects of the hormones of the hypothalamic-pituitary-thyroid axis on hemocoagulation and the fibrinolytic system are studied here. The study was conducted on 80 white male rats of the Wistar breed. The necessary blood quantity was obtained by cardiac puncture realized under ether narcosis. The basic parameters of the hemocoagulation and fibrinolytic activity of the plasma were determined by Diagnostica Stago tests (France), using an automatic coagulometer (Italy). The hormones employed in the study: Thyreotropin releasing hormone (0.06 mg/kg bw), Thyroid stimulating hormone (1 MU/kg bw), Triiodothyronine (0.08 mg/kg bw), and Thyroxin (0.08 mg/kg bw) applied s.c. for three consecutive days, extended the activated partial thromboplastine time (p less than 0.001), proto-thromboplastine time (p less than 0.001), thrombin time (p less than 0.001), reptilase time (p less than 0.001), and shortened the euglobin clot lysis time of (p less than 0.001). These data indicate that each of the hormones used causes significant changes in hemostasis by suppressing the coagulability by the intrinsic and extrinsic system pathways, and transformation of fibrinogen into fibrin. The shortened euglobim clot lysis time may be recognized as a manifestation of increased levels of plasma plasminogen activators. The results obtained show that hypothalamic-pituitary-thyroid hormones are significant regulators of hemostasis, since they cause an expressed hypocoagulation and increase plasma fibrinolytic activity.

[Beta1- and beta2-adrenergic effects on thrombocytopoiesis in rats]. / Beta1- i beta2-adrenergicheskie vliianiia na trombotsitopoéz u krys.

The influence of beta 1- and beta 2-adrenergic agent injections to rats during 3 days, on the main parameters of thrombocytopoiesis: platelet number and per cent of build up 75seleno-methionine in newly-formed platelets of rats has been studied. It is established that beta 1-adreno-stimulation with dobutamine (DB) increases both the number of platelets and the per cent of build up isotope. Practolol (PC), a beta 1-adrenergic blocking agent, used separately, and combined application of PC + DB lowered significantly the parameters studied. Salbutamol stimulation of beta 2-adrenergic receptors induced an insignificant rise in the thrombocytopoiesis parameters. beta 1-adreno-stimulation with DB results in activation, while beta 1-adrenoblocking with PC--in suppression of thrombocytopoiesis. Pretreatment with PC prevents DB stimulating effect on thrombocytopoiesis, thus evidencing the beta 1-adrenoceptor dependence on the process.