title: Effects of cryptolepine on collagen-induced aggregation and on the mobilization and metabolism of arachidonic acid by rabbit platelets.
abstract: 1. We examined the effect of cryptolepine on collagen-induced aggregation and on the mobilization, and metabolism of arachidonic acid in rabbit platelets. 2. Preincubation of platelets with cryptolepine (50-100 microM) did not affect the primary wave of aggregation but resulted in a dose-dependent, surmountable inhibition of the secondary wave of aggregation induced by collagen (5 micrograms/ml). The inhibition by cryptolepine was greater when cryptolepine was incubated with the platelets after the peak of the primary wave of aggregation. 3. Cryptolepine (50-100 microM) dose-dependently inhibited thrombin (1.5 U/ml) and A23187 (2.5 microM)-induced release of 14C[AA] from platelet membrane phospholipid pools. The percentage inhibition of A23187-induced 14C[AA] release was 31.3 +/- 4.3% (50 microM) and 79.3 +/- 5.4% (100 microM), while thrombin-induced release was inhibited by 39.2 +/- 2.4% (50 microM) and 68.2 +/- 3.6% (100 microM). 4. At near maximal concentration (100 microM) which significantly inhibited secondary aggregatory response and 14C[AA] release, cryptolepine had no effect on the platelet metabolism of 14C[AA] to thromboxane B2, HHT and 12 HETE. 5. The present findings suggest that cryptolepine inhibited collagen-induced secondary aggregation through a selective antiphospholipase-like activity. There was no effect on platelet cyclooxygenase and lipoxygenase activities of platelets.
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla 10595.
authors.forename: A O
authors.initials: AO
authors.lastname: Oyekan
authors.forename: S Y
authors.initials: SY
authors.lastname: Ablordeppey
mesh_terms: D000470:Alkaloids / Q000138:chemical synthesis / Q000494:pharmacology*; D000818:Animals; D016718:Arachidonic Acid / Q000097:blood*; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000001:Calcimycin / Q000037:antagonists & inhibitors / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D003094:Collagen / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D066298:In Vitro Techniques; D026121:Indole Alkaloids; D007211:Indoles; D008297:Male; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000138:chemical synthesis / Q000494:pharmacology*; D011804:Quinolines; D011817:Rabbits; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D026121:Indole Alkaloids; D007211:Indoles; D010975:Platelet Aggregation Inhibitors; D011804:Quinolines; D016718:Arachidonic Acid; D000001:Calcimycin; C024015:cryptolepine; D003094:Collagen; D013917:Thrombin