Prostaglandins alter the relationship between gastric hydrogen ion concentration and flow: evidence for stimulation of non‐parietal secretion in the cat

Abstract

SUMMARY1. The effect of i.v. administration of prostaglandin (PG) E2 (10-40 jug kg-' h-'), 16,16-dimethyl PGE2 (0-1-0-5 jag kg-h-'), PGE, (16)(17)(18)(19)(20) jg kg-h-1), PGA, (5-11 #ug kg-' h-') and PGF2a (40 , 3. At the dose tested, PGF2a had little effect on acid output, and did not alter the relationship between [H+] and gastric flow.4. There is a linear relationship between acid output and gastric flow and this relationship is similar during stimulation of gastric secretion by pentagastrin, histamine or insulin. Gastric acid inhibitory doses of cimetidine, atropine and somatostatin did not alter this relationship. In contrast the A-and E-type prostaglandins displaced this relationship to the right of the normal line observed with the acid stimulants alone. A-and E-type prostaglandins reduced the slope of the line relating acid output and gastric flow from -150-170 ,uequiv/ml-1 to 100-120 #equiv ml-', this being taken as evidence of dilution of the parietal H+ secretion with a non-parietal secretion.5. The volume of non-parietal gastric secretion was calculated as the gastric flow at zero acid output by extrapolation of linear plots of acid output versus gastric flow. Unstimulated gastric flow measured directly was 0 75 ml 15 min'. The calculated non-parietal flow was in the range 0-52-0 90 ml 15 min' during stimulation of gastric secretion with pentagastrin, histamine and insulin, and inhibition of pentagastrinstimulated acid secretion with cimetidine, atropine and somatostatin. PGE2 (1-51 ml 15 min-') and 16,16-dimethyl PGE2 (1-20 ml 15 min') nearly doubled the calculated non-parietal flow.

Stimulation of electrogenic chloride secretion by prostaglandin E2 in guinea‐pig isolated gastric mucosa.

“…Studies in vivo have shown that prostaglandins stimulate non-parietal secretion from mammalian stomach (rat: Bolton, Palmer & Cohen, 1978; dog: cat: Gascoigne & Hirst, 1981), and that this secretion consists principally of Na+ and Clions with smaller amounts of K+ and HC03-(dog: Miller, Henagan, Watkins & Loy, 1983;cat: Smeaton & Hirst, 1984;rat: Bunce, 1985). Studies on non-parietal secretion in mammalian isolated tissues have shown that 16,16-dimethyl-prostaglandin E2 stimulates bicarbonate secretion in rabbit gastric mucosa (Rees, Gibbons & Turnberg, 1983), although no such secretion was observed in dog gastric mucosa (Kuo, Miller & Shanbour, 1983).…”

Transmucosal electrical resistance in rabbit isolated gastric mucosa during exposure to acid.

“…The mechanism of action of prostaglandins is likely to be multifactorial (Miller, 1983). Prostaglandins stimulate the non-parietal component of gastric secretion rich in NaCl (Gascoigne & Hirst, 1981;Smeaton & Hirst, 1984;Bunce, 1985). Although there is one report that prostaglandin increased the net absorption of Na+ in the dog gastric mucosa (Chaudhury & Jacobson, 1978), in both amphibian (Schiessel, Matthews, Barzilai, Merhav & Silen, 1980) and guinea-pig gastric mucosa (Bunce & Spraggs, 1988) there is good evidence for prostaglandin stimulation of electrogenic Cl-secretion.…”