title: Effect of an impermeant arginine-modifying reagent on the responses of rabbit platelets to agonists.
abstract: The importance of surface arginyl residues in platelet aggregation was investigated by studying the effects of an impermeant arginine-modifying reagent, p-sulfonylphenylglyoxal (PSPG), on platelet responses to various agonists. Pretreatment of resuspended rabbit platelets with 2-15 mM PSPG resulted in complete inhibition of aggregation responses to ADP and 5-HT, and a concentration-dependent inhibition of the preceding shape change. Aggregation responses to thrombin also were inhibited in a concentration-dependent manner. The protective effects of antagonists of these three agonists (beta, gamma-methylene ATP for ADP, hirudin for thrombin and phentolamine for 5-HT) during pretreatment of platelets with PSPG indicated that intact arginine residues form part of the receptor sites for ADP and for thrombin. Arginine residues are not part of the 5-HT receptor site itself, but seem to be important for the maintenance of the functional integrity of this site.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000447:Aldehydes / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000097:blood*; D001667:Binding, Competitive; D002463:Cell Membrane Permeability; D006629:Hirudins / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D010658:Phenylglyoxal / Q000031:analogs & derivatives / Q000494:pharmacology*; D010974:Platelet Aggregation / Q000187:drug effects*; D011817:Rabbits; D011956:Receptors, Cell Surface / Q000187:drug effects; D011983:Receptors, Purinergic; D012702:Serotonin Antagonists / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology
chemical_list: D000447:Aldehydes; D006629:Hirudins; D011956:Receptors, Cell Surface; D011983:Receptors, Purinergic; D012702:Serotonin Antagonists; C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; D000244:Adenosine Diphosphate; C038707:4-sulfonylphenylglyoxal; D000255:Adenosine Triphosphate; D001120:Arginine; D013917:Thrombin; D010658:Phenylglyoxal; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D010646:Phentolamine