Diacylglycerol mediates the thrombin‐induced, protein kinase C and Ca2+ independent activation of the Na+/H+ exchanger in platelets

FEBS Letters

Cavallini, Lucia¹  Coassin, Mariagrazia¹  Alexandre, Adolfo¹ 

[1]Dipartimento di Chimica Biologica, Via Trieste 75, 35121 Padova, Italy

关键词: Diglyceride;    Na+/H+ exchanger;    Platelet activation;    ArA;    arachidonic acid;    BAPTA-AM;    1;    2-bis-(2-aminophenoxy)ethane-N;    N;    N′;    N′-tetraacetic acid tetraacetoxymethyl ester;    BCECF-AM;    2′;    7′-bis(2-carboxyethyl)-5(6)-carboxyfluorescein triacetoxymethyl ester;    BSA;    bovine serum albumin;    [Ca2+]i;    cytosolic free Ca2+ concentration;    ET 18-OCH3;    1-O-octadecyl-2O-methyl-rac-glycero-3-phosphorylcholine;    DiC8;    1;    2-dioctanoyl-sn-glycerol;    GF 109203X;    bisindolylmaleimide;    INDO 1AM;    1-(2-amino-5-(6-carboxyindol-2-yl)phenoxy)-2-(2′-amino-5′-methylphenoxy)ethane-N;    N;    N′;    N′-tetraacetic acid pentaacetoxymethyl ester;    NHA 5;    (N;    N-hesamethylene)amiloride;    PGI2;    prostaglandin I2 or prostacyclin;    PKC;    protein kinase C;    PMA;    phorbol;    12-myristate;    13-acetate;    PRP;    platelet-rich plasma;    R 599949 diacylglygerol kinase inhibitor II;    3-(2-(4-(bis(4-fluorophenyl)methylene)-1-piperidinyl)ethyl)-2;    3-dihydro-2-thioxo-4(1H)-quinazolinone;    RHC-80267;    1;    6-bis(cyclohexylaminocarbonylamino)hexane;    Tg;    thapsigargin;   

DOI  :  10.1016/S0014-5793(96)01364-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Treatment of aspirinated platelets with the electroneutral K⁺/H⁺ exchanger nigericin induces a decrease in intraplatelet pH as measured with the intracellular fluorescent indicator BCECF. Under these conditions, the proton permeability of the plasma membrane is unaffected. The addition of thrombin induces a rapid partial recovery of pH_i, which is completely abolished by the Na⁺/H⁺ exchanger inhibitor NHA. The effect is also evident in the presence of the PKC inhibitors GF 109203X or staurosporine and in the absence of both external (EGTA-chelated) and internal (BAPTA-chelated) Ca²⁺. This makes the thrombin-induced activation of the exchanger independent of the involvement of the hitherto described activators, namely PKC and the increase in [Ca²⁺]_i, as well of the recently reported activator arachidonic acid [Cavallini, L., Coassin, M., Borean, A., and Alexandre, A. (1996) Biochem. J. 319, 567–574], whose production requires a high [Ca²⁺]_i. The thrombin-dependent recovery of pH_i is prevented by the phospholipase C inhibitor ET 18 O-CH₃ and is mimicked by the addition of the permeable diglyceride dioctanoyl glycerol (DiC₈) exogenously supplied. The effect of thrombin and DiC₈ is unaffected by inhibition of diacylglycerol lipase and diacylglycerol kinase. These experiments identify diglyceride as a novel activator of the Na⁺/H⁺ exchanger in platelets.

【 授权许可】

Unknown