Effect of glycine on the calcium signal of thrombin-stimulated platelets

GIAMBELLUCA MS; GENDE OA

BLOOD COAGULATION & FIBRINOLYSIS : AN INTERNATIONAL JOURNAL IN HAEMOSTASIS AND THROMBOSIS.

Rapid Communications of Oxford Ltd., c1990

Lugar: Oxford, UK; Año: 2007 vol. 18 p. 303 - 308

0957-5235

In the treatment of hemorrhagic shock, infusion of a small volume of 7.5% NaCl gives an immediate hemodynamic improvement but in vitro experiments suggest that it depresses hemostatic system. Since previous reports showed that hyperosmotic glycine solutions preserved the platelet function better than hypertonic NaCl solutions, our objective was investigated if glycine changes the intracellular calcium signal. Methods: Platelets were incubated in hyperosmotic sodium glycine or glycine base and stimulated with 0.1IU/ml of thrombin. The [Ca2+]i increases were compared with an isotonic control. Platelets incubated in zero calcium/EGTA were used to study separately the effect of glycine on calcium mobilization from intracellular stores and extracellular calcium entry. Results: When NaCl was replaced by NaGly the increase of [Ca2+]i produced by thrombin was enhanced, because the calcium entry increased without  changes in  the mobilization of stored calcium. The addition of 50mM Gly to the HEPES-buffered media increases the thrombin-induced entry of calcium or manganese. Conclusions: This study demonstrated that hyperosmolar glycine solutions increase the thrombin-induced entry of calcium. This effect contrast with the impairment of the agonist-induced calcium signals by NaCl. The addition of low amounts of glycine in resuscitation solutions would be useful to reduce dysfunctional inflammatory responses without risk of bleeding but concentrated solutions could cause toxic effects.