title: Reactions of polylysine with human platelets in plasma and in suspensions of washed platelets.
abstract: The effects of polylysine on human platelets have been examined in citrated platelet-rich plasma (PRP) and in suspensions of washed platelets in various media. In PRP, polylysine caused aggregation after a lag phase. Heparin inhibited this completely. At certain concentrations of polylysine, two phases of aggregation occurred, the second being associated with release of 14C-serotonin from prelabelled platelets; this phase was inhibitable with prostaglandin E1, acetylsalicylic acid, sulphinpyrazone, adenosine, apyrase, or creatine phosphate/creatine phosphokinase. Polylysine-induced release also occurred in PRP with EDTA or hirudin as anticoagulant. In suspensions of washed platelets in Tyrode solution containing 0.35% or 4% albumin, or 1% gelatin, polylysine caused immediate platelet-to-platelet adherence and very little release of 14C-serotonin or platelet lysis. Heparin inhibited aggregation, but acetylsalicylic acid, prostaglandin E1, adenosine, apyrase, creatine phosphate/creatine phosphokinase or EDTA did not. In a modified Tyrode-albumin medium containing 1 mM magnesium but no calcium, polylysine-induced aggregation was associated with the release of 14C-serotonin which could be inhibited by acetylsalicylic acid or indomethacin; this is similar to the effect of ADP in this medium. In Tyrode solution without albumin or gelatin, polylysine-induced platelet aggregation was associated with release of a large percentage of 14C-serotonin, together with as much as 18% lysis; indomethacin inhibited this release reaction.
mesh_terms: D000418:Albumins; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D002413:Cations, Divalent; D002951:Citrates; D004492:Edetic Acid; D005780:Gelatin; D006629:Hirudins; D006801:Humans; D066298:In Vitro Techniques; D010455:Peptides / Q000494:pharmacology*; D010949:Plasma; D010974:Platelet Aggregation / Q000187:drug effects; D011107:Polylysine / Q000494:pharmacology*; D012701:Serotonin / Q000097:blood; D012996:Solutions
chemical_list: D000418:Albumins; D002413:Cations, Divalent; D002951:Citrates; D006629:Hirudins; D010455:Peptides; D012996:Solutions; D011107:Polylysine; D012701:Serotonin; D005780:Gelatin; D004492:Edetic Acid