Effects of hydrocortisone and aminophylline on the aggregation of equine plateletsin vitro

Abstract

The purpose of this study was to evaluate in vitro the effects of hydrocortisone and aminophylline on adenosine diphosphate (ADP)-induced platelet aggregation in horses. Blood samples from 30 healthy Thoroughbred horses were collected by via jugular venipuncture to assess platelet aggregation. Platelet-rich and platelet-poor plasma were prepared from all samples by centrifugation and divided into three different aliquots. In the first aliquot, platelet aggregation was measured after platelet activation with 1 µM and 0.5 µM ADP (Group A). In the other two aliquots, the effect of a 10 min preincubation with hydrocortisone (Group B) or aminophylline (Group C) on ADP-induced aggregation at final ADP concentrations of 1 µM and 0.5 µM was observed. Platelet aggregation, recorded by an aggregometer, was evaluated by measuring the maximum degree of platelet aggregation and the initial velocities of platelet aggregation were obtained. Our results demonstrated the inhibitory effect of hydrocortisone and the induction effect of aminophylline on equine platelet responses in vitro.

Ocena funkcji płytek krwi u pacjentów z endogenną hiperkortyzolemią

“…Animal models, however, indicate impaired platelet ADP-stimulated aggregation after hydrocortisone infusion. Casella et al suggest that hydrocortisone modulates the interaction between ADP and the appropriate receptor, as well as phospholipase A2 and phospholipase C activation by thromboxane, PAF, and/or ADP [16]. These results were not confirmed by Schuerholz et al, who found no alteration of platelet receptor expression by hydrocortisone in septic patients [30].…”

“…So far, few reports have been published on the effect of corticosteroids on platelet function, most of them were veterinary medicine studies [16,18], and their results indicate a suppressive effect of exogenous glucocorticosteroids on blood platelet aggregation in animals [16,19]. These observations contrast with reports on megakaryocyte function in Cushing's disease (CD) patients.…”

“…Platelet function, which plays a vital role in primary haemostasis, is much less clear in this context. Most reports so far have investigated the effect of synthetic steroids on platelet count, while there are far fewer in which platelet function was analysed, and these were predominantly performed in veterinary research [16,18]. Moreover, until now, the majority of studies have investigated the influence of exogenous steroids on platelet aggregation.…”

“…Taking into account the results of the above-mentioned reports, the sort of glucocorticosteroid and its dose should be investigated as the reason for these contrasting findings. [16,19].…”

“…In the process of coagulation three steps of thrombocyte action can be listed: adhesion, secretion, and aggregation. Collagen exposition from a damaged vessel wall leads to platelet adhesion through specific collagen receptors in the platelet cellular membrane and von Willebrand factor (vWF); during this step platelet activation takes place [16,17]. This process, in turn, leads to the secretion of biologically active substances such as thrombin, collagen, platelet activating factor (PAF), adenosine diphosphate (ADP), thromboxane A2, and serotonin, which promote platelet aggregation and inhibit natural anticoagulation factors of endothelial cells.…”