On the formation of thromboxane B2 and 12l-hydroxy-5,8,10,14-eicosatetraenoic acid (12 ho-20:4) in tissues from the guinea pig.

Homogenates of tissues from the guinea pig were incubated at 37 degrees C for 30 min and the amounts of thromboxane B2 and 12L-hydroxy-5,8,10,14-eicostetraenoic acid (12ho-2-:4) formed from endogenous arachidonic acid were determined by multiple-ion analysis. Lung and spleen homogenates produced 7146 +/- 500 ng/g and 3046 +/- 542 ng/g, respectively, of thromboxane B2 and 15 122 +/- 3536 ng/g and 29 516 +/- 1966 ng/g, respectively, of 12ho-20:4. The amounts of both compounds in homogenates of kidney, stomach, liver, heart and whole blood were at least 10-times lower than those found in lung and spleen. 5,8,11,14-Eicostetraynoic acid and nordihydroguaiaretic acid inhibited 12ho-20:4 formation in spleen homogenates whereas indomethacin and arachidonic acid stimulated it.