Altered calcium signaling in platelets from nitric oxide-deficient hypertensive rats

BACKGROUND: In the present study we have analyzed the mechanisms of calcium entry and mobilization in platelets obtained from rats chronically treated with the nitric oxide synthesis inhibitor, N-nitro L-arginine methyl ester [L-NAME, 40 mg/kg/day, 5 days). The platelets were obtained the day of the experiment, washed and loaded with fura-2. The intracellular calcium levels were determined in suspension of cells by means of fluorescence spectroscopy. RESULTS: Basal calcium levels were always elevated in the platelets of the L-NAME-treated rats, both in the presence and in the absence of extracellular calcium. The administration of thrombin in the absence and in the presence of extracellular calcium induced important elevations in calcium levels that were always of greater magnitude in the platelets of the L-NAME-treated rats than in those of the controls. The addition of calcium to thapsigargin-treated platelets produced a massive elevation in calcium levels in both groups that was significantly greater in the platelets obtained from the hypertensive rats than in those of the controls. CONCLUSIONS: It is concluded that the arterial hypertension induced by the reduction of nitric oxide alters the regulation of platelet calcium levels so that elevated baseline levels and calcium entry and mobilization are enhanced. This could be the result of direct or indirect effects of the lack of nitric oxide synthesis in platelets or in other tissues

Homeostasis del calcio en plaquetas de ratas cirróticas / David Iyú Espinosa; dirección y supervisión de Noemí Marín Atucha y María Clara Ortiz Ruiz.

Tesis-Universidad de Murcia.MEDICINA ESPINARDO. DEPOSITO. MU-Tesis 850.Consulte la tesis en: BCA. GENERAL. ARCHIVO UNIVERSITARIO. T.M. 2967

Role of homocysteine and folic acid on the altered calcium homeostasis of platelets from rats with biliary cirrhosis

Previously, we have found that intracellular calcium homeostasis is altered in platelets from an experimental model of liver cirrhosis, the bile-duct ligated (BDL) rat; these alterations are compatible with the existence of a hypercoagulable state. Different studies indicate that cholestatic diseases are associated with hyperhomocysteinemia; thus, we hypothetized that it could contribute to those platelet alterations. In the present study, we have investigated the role of homocysteine (HCY) in platelet aggregation and calcium signaling in the BDL model. The effect of chronic folic acid treatment was also analyzed. Acute treatment with HCY increased the aggregation response to ADP and calcium responses to thrombin in platelets of control and BDL rats. Capacitative calcium entry was not altered by HCY. Chronic treatment with folic acid decreased platelet aggregation in control and BDL rats, but this decrease was greater in BDL rats. In folic acid-treated rats, thrombin-induced calcium entry and release were decreased in platelet of control rats but unaltered in BDL rats; however, capacitative calcium entry was decreased in platelets of control and BDL rats treated with folic acid. Reactive oxygen species were produced at higher levels by BDL platelets after stimulation with HCY or thrombin and folic acid normalized these responses. HCY plays a role in the enhanced platelet aggregation response of BDL rats, probably through an enhanced formation of ROS. Folic acid pretreatment normalizes many of the platelet alterations shown by BDL rats

Bile Acids Do Not Contribute to the Altered Calcium Homeostasis of Platelets from Rats with Biliary Cirrhosis.

© 2017. This manuscript version is made available under the [CC-BY 4.0] license http://creativecommons.org/licenses/by/4.0/ This document is the Accepted Manuscript version of a Published Work that appeared in final form in [Frontiers in Physiology]. To access the final edited and published work see [10.3389/fphys.2017.00384

Altered calcium signalling in platelets from bile-duct-ligated rats

A B S T R A C T In the present study, we have analysed the mechanisms of Ca 2+ entry and release in platelets obtained from BDL (bile-duct-ligated) rats, 11-13 days and 4 weeks after surgery. Platelets were washed and loaded with fura-2, and [Ca 2+ ] i (cytosolic Ca 2+ concentration) was determined in cell suspensions by means of fluorescence spectroscopy. Basal [Ca 2+ ] i was similar in platelets from BDL rats compared with those from their respective controls, both in the absence and presence of extracellular Ca 2+ . Platelet stimulation with thrombin in the absence and presence of extracellular Ca 2+ induced a rapid rise in [Ca 2+ ] i that was of greater magnitude in platelets from BDL rats than in controls. Ca 2+ storage was significantly elevated in platelets from BDL rats, as well as the activity of SERCA (sarcoplasmic/endoplasmic-reticulum Ca 2+ -ATPase). Capacitative Ca 2+ entry, as evaluated by inhibition of SERCA with thapsigargin, was also altered in platelets from BDL rats, having lower rates of Ca 2+ entry. In conclusion, chronic BDL alters intracellular Ca 2+ homoeostasis in platelets, such that an enhanced Ca 2+ release is evoked by thrombin, which may be due to an increased amount of Ca 2+ stored in the intracellular organelles and secondary to an enhanced activity of SERCA. These alterations are already evident before cirrhosis has completely developed and occurs during the cholestasis phase

Platelet function and microvesicle generation in patients with hemophilia A

Our results do not support any effect of FVIII on platelet function in patients with severe HA treated under the regime of prophylaxi

Platelet function and microvesicle generation in patients with hemophilia A

Our results do not support any effect of FVIII on platelet function in patients with severe HA treated under the regime of prophylaxi