Increased blood level of prostaglandin-like substances during cardiopulmonary bypass in the dog.

Total heart-lung bypass (TBP) for open-heart surgery is often accompanied by a progressive reduction of systemic blood pressure. Since the lung is the main site of elimination of prostaglandins (PGs) from venous blood, TBP may lead to an increase in blood content of vasodilator PGs. TBP was performed in dogs and blood level of prostaglandinlike substances (PLS) was monitored continuously by a bio-assay method. The concentration of PLS increased during TBP to 0.8 ng.cm(-3) blood (in PGE2 equivalents). Restoration of normal circulation led to the disappearance of PLS from the blood. The increase in PLS during TBP was abolished by indomethacin. This was invariably accompanied by elevation of systemic blood pressure. It is suggested that an increased concentration of vasodilator PLS during TBP may contribute to the hypotension observed in total body perfusion.