A comparison of human pulmonary arterial and venous prostacyclin and thromboxane synthesis--effect of a thromboxane synthase inhibitor.

The amounts of 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) and thromboxane B2 (TxB2) produced by the endothelial surfaces of paired samples of human pulmonary arteries and veins, obtained from patients undergoing thoracic surgery, were measured. The amounts of 6-keto-PGF1 alpha and TxB2 produced by arteries compared with veins were not different. However, both arteries and veins produced more 6-keto-PGF1 alpha than TxB2, the ratio being approximately 7.5:1 for both. 6-keto-PGF1 alpha synthesis by arteries was significantly correlated with that produced by veins but the relative amounts of TxB2 were not correlated. 6-keto-PGF1 alpha synthesis was correlated with TxB2 synthesis for veins but not for arteries. 8 of the 12 arterial samples exhibited some degree of intimal fibrosis. Incubation with the thromboxane synthase inhibitor, dazoxiben , caused a significant inhibition of vascular TxB2 synthesis and a significant increase in 6-keto-PGF1 alpha synthesis. In 3 of the 5 cases the increase in 6-keto-PGF1 alpha was too large to be explained by the fall in TxB2.