High glucose enhances transient receptor potential channel canonical type 6-dependent calcium influx in human platelets via phosphatidylinositol 3-kinase-dependent pathway.
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.
Liu
Daoyan
D
Med. Klinik, Department of Nephrology, Charité Campus Benjamin Franklin, Berlin, Germany.
Maier
Alexandra
A
Scholze
Alexandra
A
Rauch
Ursula
U
Boltzen
Ulrike
U
Zhao
Zhigang
Z
Zhu
Zhiming
Z
Tepel
Martin
M
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
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