Stimulation of HCO3- secretion by the prostaglandin E2 analog enprostil: studies in human stomach and rat duodenum.

This study investigated the action of enprostil, a synthetic analog of PGE2, on gastric HCO3- secretion in humans and on duodenal HCO3- secretion in the anesthetized rat. A previously validated 2-component model was used to calculate gastric HCO3- and H+ secretion in 10 human subjects. Compared to placebo, a single 70 micrograms oral dose of enprostil increased basal gastric HCO3- secretion from 1810 +/- 340 to 3190 +/- 890 mumol/hr (P less than 0.05). In addition, enprostil reduced basal gastric H+ secretion from 5240 +/- 1140 to 1680 +/- 530 mumol/hr (P less than 0.02). Enprostil also increased HCO3- secretion and reduced H+ secretion during intravenous pentagastrin infusion. In the rat, duodenal HCO3- secretion was measured by direct titration in situ using perfused segments of duodenum just distal to the Brunner gland area and devoid of pancreatic and biliary secretions. Addition of enprostil (10 micrograms/ml) to the duodenal bathing solution increased duodenal HCO3- secretion from 6.3 +/- 1.3 to 15.1 +/- 2.0 mumol/cm X hr (P less than 0.01, n = 6). The stimulatory action of enprostil on duodenal HCO3- secretion at 10 micrograms/ml was comparable in magnitude and duration to that of 10 micrograms/ml natural PGE2. In summary, the PGE2 analog enprostil stimulated gastroduodenal HCO3- secretion, effects which may be beneficial in protection of the gastroduodenal mucosa against luminal acid.