[Changes in plasma thromboxane B2 and 6-keto-prostaglandin F1 alpha in bronchial asthma]

We measured the plasma levels of TXB2, a stable metabolite of TXA2, and 6-K-PGF1 alpha, a stable metabolite of PGI2, in 28 asthmatics (16 of extrinsic type, 12 of intrinsic type) during symptomatic period and asymptomatic period respectively with radioimmunoassay. At the same time, plasma TXB2 and 6-K-PGF1 alpha were measured in 30 normal subjects for control. The results were as follows: (1) In the extrinsic asthmatics: The plasma TXB2 level measured during symptomatic period was significantly higher than that during asymptomatic period (P less than 0.05), while the plasma level of 6-K-PGF1 alpha measured during symptomatic period was significantly lower than that of normal subjects (P less than 0.01). The ratio of TXB2/6-K-PGF1 alpha measured during symptomatic period was significantly higher than that measured during asymptomatic period and that measured in the normal subjects (P less than 0.05). (2) In intrinsic asthmatics: The plasma 6-K-PGF1 alpha level measured during symptomatic period was significantly lower than that of normal subjects. There was no significantly difference between either plasma TXB2 level or ratio of TXB2/6-K-PGF1 alpha measured during symptomatic period and that measured during asymptomatic period as well as that of normal subjects. From these results it is suggested that (1) The TXA2 and PGI2 may play a different role in different types of asthma, (2) The imbalance between TXA2-PGI2 may be one of the important factors that take part in the pathogenesis of extrinsic asthma.