Changes in Urinary Thromboxane Level in Man During Cardiopulmonary Bypass

Abstract

We measured urinary and plasma level of prostaglandins during cardiopulmonary bypass (CPB) and their clinical significance. The urinary levels of NAG was also measured at the same time.
Urinary and plasma levels of TXB₂ and 6keto PGF_1α were increased upon initiation of CPB. The urinary NAG level increased significantly (p<0.001). Plasma TXB₂ levels as expected from the urinary TXB₂ and 2, 3dinor-TXB₂ level was higher than the measured plasma TXB₂ concentration, showing increasese in TXB₂ originating from the kidney. However Plasma 6ketoPGF_1α as expected from the urinary 6ketoPGF_1α level was same to the measured plasma 6ketoPGF_1α concentration, showing no increased in 6ketoPGF_1α originating from the kidney.
It is possible that the elevation of urinary TXB₂ level is due to the massive increase in TXA₂ originating from the kidney when a hypoxic condition is indused by hypotension and lowered perfusion in the kidney, in addition to the increased excretion of platelet derived TXA₂ during CPB.
Furthermore, the significant correlation (r=0.77, p<0.01) was observed in NAG and urinary TXB₂, thus the increased production of TXA₂ appears to inhibit the functions of the renal proximal tubules.