Thromboxane B2 release and 3H-noradrenaline accumulation by a synaptosomal fraction of rat brain.

Release of thromboxane B2 (TXB2) and accumulation of 3H-noradrenaline (3H-NA) by a synaptosomal fraction of rat brain were investigated. TXB2 release was temperature-dependent and was inhibited by three different TX-synthetase inhibitors: imidazole, 9,11-azoprosta-5,13-dieonic acid (AZO) and 11,9-epoxyiminoprosta-5,13-dionic acid (EPI). While high concentrations of imidazole decreased the 3H-NA accumulation in the synaptosomes significantly, AZO and EPI were ineffective. The results show that TX synthesis is not essential for 3H-NA uptake and the effect of imidazole in 3H-NA accumulation is unrelated to its inhibitory effect on the enzyme TX-synthetase.