Prostaglandin F and E levels during endotoxin-induced pulmonary hypertension in calves.

Prostaglandin F and E (PGF and PGE) concentrations in sequential blood samples obtained simultaneously from the pulmonary artery (PA) and pulmonary vein (PV) during endotoxin-induced pulmonary hypertension in calves were determined by radioimmunoassay. Three groups of calves were studied. In nine control calves in which no endotoxin was given PA pressure and PGF and PGE concentrations in four pairs of samples taken at 0, 5, 15, and 45 min did not change. In 17 calves given 1 mg E. coli endotoxin, PGF concentrations were increased significantly in the PV and to a lesser degree in the PA in the 15-and 45-min samples. The increased PGF concentration in the 15-min sample corresponded to an increased PA pressure of 74 plus or minus 4 mmHg (mean plus or minus SE). In three of the endotoxin-treated calves studied a second time and three separate calves indomethacin pretreatment completely blocked the hemodynamic effect of endotoxin as well as PGF release. PGE concentrations did not change in either group. These data suggest that endotoxin-induced pulmonary hypertension may be mediated by PGF, a known pulmonary pressor agent in the bovine, and that blockade of this effect by indomethacin may be due to inhibition of prostaglandin synthesis and/or release.