Response of the human cardia sphincter to circulating prostaglandins F2ALPHA and E2 and to antiinflammatory drugs.

The effects on intraluminal pressure in the oesophagus, the cardiac sphincter, and the gastric fundus of intravenous prostaglandin F2alpha, E2, And of rectal indomethacin were studies in 41 subjects. Intravenous infusion of prostaglandin F2alpha (0-05 to 0-8 mug kg-minus1) produced marked, dose-related and sustained elevation of cardiac sphincter pressure without significantly affecting oesophageal peristalsis or gastric fundal motility. Sphincteric relaxation during swallowing was prolonged. Plasma gastrin levels were unchanged. Intravenous infusion of PGE2 (0-08 mug kg-minus1 min-minus) inhibited sphincter contractions to serial bolus intravenous injections of pentagastrin (0-1 or 0-2 mug kg-minus 1). Rectal indomethacin (200 mg) resulted in a riseof cardiac sphincter pressure, suggesting that endogenous synthesis of an inhibitory (E-type) prostaglandin was suppressed. The results indicate that prostaglandin E2 may be concerned in the regulation of cardiac sphincter tone in man, whilst prostaglandin F2alpha may be useful in the treatment of gastrooesphageal reflux.