Structure and quantitative determination of the major urinary metabolite of thromboxane B2 in the guinea pig.

2,3-Dinor-thromboxane B2 was the major urinary metabolite of thromboxane B2 in the guinea pig. The structure was assessed mainly by mass spectrometric analysis of a number of derivatives of the metabolite and by chemical degradation by oxidative ozonolysis. A method for quantitative determination of 2,3-dinor-thromboxane B2 in guinea pig urine based on multiple ion analysis and octadeuterated 2,3-dinor-thromboxane B2 as internal standard was developed. The basal excretion of the metabolite was 65 +/- 36 (S.D.) ng/kg x 24 h (n = 19; range 19--140 ng). This level corresponded to an endogenous synthesis of 543 +/- 300 ng of TXB2. No increase in the excretion was seen after anaphylaxis, in contrast to what has earlier been reported for PGF2 alpha.