Comparative Activities of Agonists of Active Duodenal Bicarbonate Secretion in the Guinea Pig

Abstract

The comparative activity of agonists of duodenal bicarbonate secretion was studied in the anesthetized guinea pig, where the duodenal lumen was perfused with 24 mmol/l NaHCO₃ to ensure active secretion of bicarbonate. Agonists were infused alone and in combination. Dibutyryl 3’,5’-cyclic adenosine monophosphate, vasoactive intestinal polypeptide (VIP) and prostaglandin E₂ (PGE₂) were strong stimulants of bicarbonate secretion. Theophylline, dibutyryl 3’,5’-cyclic guanosine monophosphate, glucagon and prostaglandin F_2α (PGF_2α) were weaker agonists, and secretin had no effect. Combinations of any two of VIP, PGE₂ and glucagon depressed bicarbonate secretion, whereas combinations of PGE₂ and PGF_2α, VIP and PGE₂, and glucagon and PGF_2α increased bicarbonate secretion. The data indicate that cAMP and other secondary messengers may mediate duodenal bicarbonate secretion.

Cystic fibrosis transmembrane conductance regulator and Na+ channel subunits mRNA transcripts, and Cl− efflux, show a different distribution in rat duodenum and colon

“…Aliquots of 0.5 mL were removed, 5 μ L of 10% BSA was added, and the mixture was incubated in a shaking water bath at 37 °C for exactly 2 min, then 5 μ L of PBS (for basal determination of cAMP) or 5 μ L of VIP was added to the incubation solution. This gave a final concentration of 5 × 10 −7 m for VIP, corresponding to doses having maximum stimulatory effect on duodenal HCO secretion in our studies with the anaesthetized guinea‐pig (Odes et al. 1994, Reimer et al.…”

Acute increase, stimulated by prostaglandin E2, in glucose absorption via the sodium dependent glucose transporter-1 in rat intestine

“…In mice and rats mRNA for the PGE 2 receptor subtypes EP2R and EP4R has been detected in the intestinal mucosal layer 910PGE 2 was previously shown to stimulate adenylate cyclase in rat intestinal epithelial cells via a receptor mediated mechanism,11 and to enhance bicarbonate secretion in guinea pig intestine 12. The mRNA expression of G s linked EP2R and EP4R,10 the observed activation of adenylate cyclase by PGE 2 ,11 and the reported stimulation of 3- O -methylglucose uptake by dbcAMP4 in enterocytes suggested that PGE 2 should enhance intestinal glucose absorption.…”

Interaction between neurokinin A, VIP, prostanoids, and enteric nerves in regulation of duodenal function

“…It is possible that the neural mechanisms involved in VIP-stimulated secretion may be suppressed by NKA. Alternatively, PGE 2 , which we believe to be released by NKA, may decrease VIP-stimulated alkaline secretion as has been shown in guinea pigs (24). Furthermore, the notion that VIPstimulated duodenal secretion of bicarbonate may be negatively modulated by prostaglandins is supported by the finding that the effect of VIP on luminal alkalinization is potentiated by indomethacin (35).…”