Human arterial and venous segments from patients under-going operations when incubated in Tris buffer both alone and with arachidonic acid were able to produce thromboxane B2 (assessed by radioimmunoassay). Thromoboxane B2 (TxB2) production was progressive in time (till 40 min.) and was enhanced by the addition of 1mM norepinephrien. Contamination of tissues by platelet was checked and platelets did not contribute to thromboxane formation. The investigation of the conversions of 1-14C arachidonic acid by vascular tissue indicated that human vascular tissues produce the metabolites of the cyclooxygenase dependent pathway and that prostacyclin is the main metabolite with a PGI2/TxA2 ratio of 4:1. The arterial wall was found to posses an active lipoxygenase dependent pathway. Thromboxane production by intimal cells was neglible and the main source of thromboxane was the media. The production of thromboxane did not change in relation to age, but arterial segments from men produced significantly larger amounts of thromboxane than those from women.
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