Transcellular metabolism of leukotriene A4 by rabbit blood cells: lack of relevant LTC4-synthase activity in rabbit platelets.
The objective of this study was to determine the transcellular metabolism of leukotriene A4 by rabbit blood cells. mixed peripheral blood leukocyte preparations with and without platelets in a ratio of 1:40 were challenged with the Ca(2+)-ionophore A23187. 5-Lipoxygenase metabolites production was assessed by RP-HPLC coupled with diode-array UV detection. In light of the observation that leukotriene C4 production in leukocyte-platelet coincubation was the same as with leukocytes alone, mixed coincubation of human and rabbit blood cells was tested. Rabbit leukocytes with human platelets resulted in a significant increase of leukotriene C4 production, while no changes were observed in human leukocytes with or without rabbit platelets. In agreement with these results, intact rabbit platelets or rabbit platelet lysates, unlike human platelets, were not able to convert synthetic leukotriene A4 free acid to leukotriene C4. These data provide evidence that rabbit leukocytes are able to make a significant amount of leukotriene A4 available for transcellular metabolism, while rabbit platelets, unlike human platelets, lack leukotriene C4-synthase activity.
Sala
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Center for Cardiopulmonary Pharmacology, School of Pharmacy, University of Milano, Italy.
Testa
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Nobili
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Folco
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D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D018920:Coculture Techniques; D005982:Glutathione Transferase / Q000378:metabolism; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D017572:Leukotriene A4 / Q000032:analysis / Q000097:blood / Q000378:metabolism*; D011817:Rabbits; D013056:Spectrophotometry, Ultraviolet
D007476:Ionophores; D017572:Leukotriene A4; D000001:Calcimycin; D001094:Arachidonate 5-Lipoxygenase; D005982:Glutathione Transferase