title: Effect of nicotine on the formation of prostacyclin-like activity and thromboxane in rabbit aorta and platelets.
abstract: The effect of nicotine on the bioformation of prostacyclin (PGI2) and of thromboxane (Tx)B2 in rabbit aorta and platelets, respectively, was investigated. Rabbit aortic rings were incubated with [14C]-arachidonic acid ( [14C]-AA) and the incubation products were separated with thin layer chromatography (t.l.c.). Alternatively, the aortic rings were incubated without substrate and their spontaneous formation of platelet anti-aggregatory activity was measured. Rabbit platelet microsomes were incubated with [14C]-AA and the products formed were separated with t.l.c. Rings of aorta were found to be incapable of converting added [14C]-AA to labelled 6-keto-PGF1 alpha (the stable hydrolysis product of PGI2). Rings of aorta incubated in saline medium spontaneously formed PGI2-like activity. This formation was dose-dependently inhibited by nicotine, with an I50 of about 10(-4) M. Platelet microsomes converted [14C]-AA to labelled TxB2. This formation was unaffected by nicotine. It is concluded that a true difference in sensitivity to nicotine exists between cyclo-oxygenase in rabbit aorta and platelets. The data also demonstrate a tissue difference between rabbit aorta and platelets concerning their utilization of exogenous AA as substrate in the formation of platelet active compounds.
mesh_terms: D000243:Adenosine Deaminase / Q000494:pharmacology; D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism; D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism*; D011464:Epoprostenol / Q000096:biosynthesis* / Q000097:blood; D005260:Female; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009538:Nicotine / Q000494:pharmacology*; D011817:Rabbits; D013929:Thromboxane B2 / Q000096:biosynthesis* / Q000097:blood; D013931:Thromboxanes / Q000096:biosynthesis*
chemical_list: D013931:Thromboxanes; D013929:Thromboxane B2; D009538:Nicotine; D011464:Epoprostenol; D000243:Adenosine Deaminase; D007213:Indomethacin