Role of Na+ and K+ on the increased 5-HT secretion from platelets of spontaneously hypertensive rats

Baudouin-Legros, Maryvonne; Dard, B; Guicheney, Pascale

doi:10.1016/0049-3848(86)90256-2

Cited by 2 publications

(2 citation statements)

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“…1B), indicating that the compounds acted at the level of the plasmatic membrane SERT. We then investigated whether the modulators of Tyrphosphorylation affected the efflux of pre-loaded [ [11][12][13]. Neither the monensininduced [Na + ] c increase (not shown), nor the efflux of labelled serotonin were affected by platelet pre-treatment with the inhibitors of either Src-kinases (PP2 and SU6656) or Tyr-phosphatases (pervanadate) (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Under these conditions a 5-HT efflux takes place from the dense granules to the cytosol and from the cytosol to the extra-cellular compartment. Serotonin efflux from platelet cytosol is also induced by increasing the cytosolic concentration of Ca 2+ or Na + [11][12][13]. It has been postulated that this process occurs through SERT, which is a hydrophobic polypeptide with 12 membrane-spanning segments containing multiple consensus sites for various protein kinases in the cytosolic domains [3,14].…”

Section: Introductionmentioning

confidence: 99%

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Serotonin (5-HT) Transport in Human Platelets is Modulated by Src-Catalysed Tyr-Phosphorylation of the Plasma Membrane Transporter SERT

Zarpellon

Donella‐Deana²,

Folda³

et al. 2008

Cell Physiol Biochem

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Background/Aim: platelets possess tightly regulated systems for serotonin (5-HT) transport. This study analysed whether the 5-HT transport mediated by the plasma-membrane transporter SERT is regulated by its Tyr-phosphorylation. Methods: 5-HT transport was determined by filtration techniques, while immunoblotting procedures were adopted for detecting the Tyr-phosphorylation of SERT in human platelet fractions. Results: 5-HT accumulation in platelets pre-treated with reserpine, which prevents the neurotransmitter transport into the dense granules, decreased upon cellular exposure to PP2 and SU6656, two structurally unrelated inhibitors of Src-kinases. By contrast, the protein Tyr-phosphatase inhibitor pervanadate increased the 5-HT accumulation. Anti-SERT immunostaining of the platelet fractions showed a major band displaying an apparent molecular mass of 50 κDa, indicating that, during the analytical procedure, SERT underwent proteolysis, which was counteracted by addition of 4 M urea in the cellular disrupting medium. The Tyr-phosphorylation degree of SERT immunoprecipitated from membrane extracts decreased by platelet treatment with SU6656 or PP2, and enhanced upon pervanadate treatment. The anti-SERT immunoprecipitates displayed anti-Src immunostaining and in vitro kinase activity towards a Src-specific peptide-substrate. Platelet treatment with PP2 or SU6656 also caused a decrease in the imipramine binding to platelets. It was concluded that the Src-mediated SERT Tyr-phosphorylation regulates the 5-HT transport by affecting the neurotransmitter binding sites.

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Section: Resultsmentioning

confidence: 99%