Evaluation of the role of the F prostaglandins in canine bile flow.

Prostaglandin F2 alpha (PGF2 alpha) has been shown to be an effective stimulant of hepatic bile flow producing a specific chloride rich bile. Subsequent evaluation by radioimmunoassay has shown that prostaglandin F compounds are present in relatively large amounts in canine hepatic bile. This study evaluates the effect of PGF2 alpha administration and of prostaglandin synthetase inhibition by aspirin and indomethacin on bile flow and radioimmunoassayable prostaglandin F (iPGF) secretion. Chronic, canine bile fistula preparations were utilized and the enterohepatic circulation was maintained by intravenous bile salts. Bile volume and composition were evaluated by standard techniques as well as bile PGF concentration by radioimmunoassay during bile salt infusion and during bile salt and PGF2 alpha, aspirin and indomethacin infusion in varying doses. Both aspirin and PGF2 alpha were potent stimulants of hepatic bile flow with aspirin producing a chloride rich bile similar to that produced by PGF2 alpha. PGF2 alpha produced dose related increases in bile iPGF concentration and output indicating that as the systemic concentration increases during infusion of PGF2 alpha the lipid appears in bile. Aspirin in the highest dose administered, decreased iPGF concentration in bile while output was unchanged. Indomethacin was ineffectual in consistently altering bile flow or iPGF secretion. This study demonstrates that iPGF is present in canine bile, that its concentration can be altered by prostaglandin infusion while prostaglandin synthetase inhibition has minimal effects on bile iPGF secretion.