Influence of the lung on arterial levels of endogenous prostaglandins E and F.

Arterial and mixed venous levels of immunoreactive prostaglandins E (IRPGE) and F (IRPGF) were measured before, during, and after total cardiopulmonary bypass (CPB) or left-heart bypass (LHBP) in 22 anesthetized dogs. Mean arterial levels of IRPGE and IRPGF increased with time on bypass from prebypass levels of less than 0.01 ng/ml to 6.12 +/- 1.71 and 4.85 +/- 1.31 ng/ml, respectively, after 3-4 h of CPB. There was no significant difference between right atrial and femoral arterial prostaglandin levels during CPB. Upon restoration of normal pulmonary blood flow, arterial levels decreased toward control, and significant pulmonary artery-left ventricular gradients were observed. During LHBP, with similar extracorporeal pathophysiological conditions as CPB, but with the lungs normally perfused, arterial levels of IRPGE and IRPGF were not significantly different from prebypass levels. These data suggest that elevations in endogenous arterial IRPGE and IRPGF are due to the absence of the prostaglandin clearance function of the lung when blood is temporarily diverted from the pulmonary circulation during CPB. Therefore, the prostaglandin clearance function of the lung appears to be important in regulating arterial levels of endogenous prostaglandins E and F.