title: High glucose enhances transient receptor potential channel canonical type 6-dependent calcium influx in human platelets via phosphatidylinositol 3-kinase-dependent pathway.
abstract: BACKGROUND
  Transient receptor potential canonical type 6 (TRPC6) channels mediating 1-oleoyl-2-acetyl-sn-glycerol (OAG)-induced calcium entry have been identified on human platelets. In the present study we tested the hypothesis that hyperglycemia increases the expression of TRPC6 channels.
  
  
  RESULTS
  Platelets from healthy control subjects and patients with type 2 diabetes mellitus were incubated with glucose and calcium influx was measured using the fluorescent dye technique. TRPC channel protein expression was investigated using immunofluorescence and fluorescence microscopy of single platelets. Administration of 25 mmol/L glucose significantly enhanced the OAG-induced calcium influx, which was attenuated by inhibitors of the phosphatidylinositol 3-kinase, wortmannin or LY294002. The glucose-enhanced and OAG-induced calcium influx was concentration- and time-dependent. Glucose significantly increased the TRPC6 protein expression in platelets to 131+/-12% (n=33; P<0.05), whereas the expression of TRPC1, TRPC3, TRPC4, or TRPC5 were unchanged. The glucose-induced TRPC6 expression was significantly attenuated in the presence of wortmannin or LY294002. Platelets from patients with type 2 diabetes mellitus showed increased TRPC6 expression compared to nondiabetic individuals (P<0.05).
  
  
  CONCLUSIONS
  The study indicates that high glucose increases TRPC6 channel protein expression on the platelet surface which is mediated by a phosphatidylinositol 3-kinase-dependent pathway.
authors.affiliation: Med. Klinik, Department of Nephrology, Charité Campus Benjamin Franklin, Berlin, Germany.
authors.forename: Daoyan
authors.initials: D
authors.lastname: Liu
authors.forename: Alexandra
authors.initials: A
authors.lastname: Maier
authors.forename: Alexandra
authors.initials: A
authors.lastname: Scholze
authors.forename: Ursula
authors.initials: U
authors.lastname: Rauch
authors.forename: Ulrike
authors.initials: U
authors.lastname: Boltzen
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Zhao
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Zhu
authors.forename: Martin
authors.initials: M
authors.lastname: Tepel
mesh_terms: D000368:Aged; D000730:Androstadienes / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D016022:Case-Control Studies; D002867:Chromones / Q000494:pharmacology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D003925:Diabetic Angiopathies / Q000097:blood / Q000209:etiology; D004075:Diglycerides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D005947:Glucose / Q000494:pharmacology; D006801:Humans; D006943:Hyperglycemia / Q000097:blood*; D066298:In Vitro Techniques; D008875:Middle Aged; D008954:Models, Biological; D009025:Morpholines / Q000494:pharmacology; D019007:P-Selectin / Q000097:blood; D019869:Phosphatidylinositol 3-Kinases / Q000097:blood*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015539:Platelet Activation / Q000187:drug effects; D050052:TRPC Cation Channels / Q000097:blood*; D000074287:TRPC6 Cation Channel; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D001786:Blood Glucose; D002867:Chromones; D004075:Diglycerides; D004791:Enzyme Inhibitors; D005947:Glucose; D009025:Morpholines; D019007:P-Selectin; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; D000077191:Wortmannin; C117032:TRPC6 protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C038237:1-oleoyl-2-acetylglycerol