title: An extract of rat submandibular glands activates platelets and enhances cutaneous vascular permeability in rats and guinea pigs.
abstract: Washed, [3H]serotonin-labeled platelets from rats and guinea pigs were stimulated in vitro with a novel protein extracted from rat submandibular salivary glands (RS-PAP) and with the phospholipid platelet- activating factor 1-0-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine (AGEPC). Rat platelets, which are refractory to AGEPC stimulation, underwent shape-change, aggregation and secretion of [3H]serotonin in response to graded doses of RS-PAP and AGEPC. Intradermal injections of histamine, RS-PAP and AGEPC caused a dose-related increase in local microvascular permeability in rats, as measured by the extravasation of plasma containing Evans blue dye. Similarly, histamine, RS-PAP and AGEPC increased cutaneous vascular permeability when injected intradermally in guinea pigs. The vascular permeability induced by histamine and RS-PAP, but not by AGEPC, was partially inhibited by pretreatment with an antihistamine (diphenhydramine HCl). Pretreatment of guinea pigs with captopril, an inhibitor of angiotensin-converting enzyme (ACE), partially inhibited cutaneous responses to subsequent intradermal injections of histamine, RS-PAP and AGEPC. Regardless of pretreatment with diphenhydramine or captopril, skin test sites injected with large amounts of RS-PAP became hemorrhagic within minutes and necrotic within 12 hours.
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects*; D002199:Capillary Permeability / Q000187:drug effects*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007271:Injections, Intradermal; D008297:Male; D010972:Platelet Activating Factor / Q000494:pharmacology; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D012471:Salivary Proteins and Peptides / Q000494:pharmacology*; D012701:Serotonin / Q000097:blood; D012867:Skin / Q000098:blood supply
chemical_list: D010972:Platelet Activating Factor; D012471:Salivary Proteins and Peptides; D012701:Serotonin