Thromboxane synthesizing system in rat liver.

Thromboxane B2 (TXB2), along with other primary prostaglandins, was synthesized when rat liver microsomes were incubated with radioactive arachidonic acid. TXB2 was identified directly by chemical ionization mass spectrometry and indirectly by using specific inhibitors of TX synthetase, viz., imidazole and OKY-1555 ((E)-3(4-(3-pyridyl-methyl) phenyl)-2 methyl acrylic acid HCl). The supernatant fraction obtained after centrifugation at 105,000 X g for 60 min contained a possible regulatory component that suppressed thromboxane synthesis. The regulatory influence is lost after partial hepatectomy.