Effects of various prostaglandin synthesis inhibitors on the tone of the lower oesophageal sphincter in man

The role of endogenous prostaglandins in the modulation of lower oesophageal sphincter (LES) function has been assessed by giving three structurally unrelated cyclooxygenase inhibitors and monitoring their acute effects on LES tonus and platelet thromboxane (TX) B2 production in 20 healthy volunteers. In a double-blind, placebo-controlled, cross-over study, IV injection of soluble salts of acetylsalicylic acid and indomethacin elicited a transient increase in LES tonus of approximately 50% over baseline. A similar pattern was observed after the rectal administration of indomethacin. In contrast, indoprofen had no measurable effect on LES tones, despite comparable inhibition of platelet cyclooxygenase activity. This may have been due to the markedly different tissue distribution of the drug. The results suggest that endogenous prostaglandins physiologically exert an inhibitory influence on LES function.