Effect of omeprazole on sodium and potassium output in pentagastrin-stimulated equine gastric contents.

The research study investigates the impact of the drug omeprazole on the output of sodium and potassium in gastric contents of horses stimulated by pentagastrin. The results demonstrate that while sodium levels increased significantly post-omeprazole treatment, potassium levels remained unchanged.

Research Methodology

• The study was conducted on adult cross-bred horses (4 geldings and 1 mare) that underwent surgery for the insertion of a gastric cannula, which enables researchers to collect gastric contents continuously by gravity drainage.
• In the experiment setup, the horses were lightly restrained in stocks, the gastric cannula was opened, and a catheter was inserted into the horse’s jugular vein.
• Over a period of 5 hours, gastric content was collected every 15 minutes to measure its volume, pH, and concentration of sodium ([Na+]) and potassium ([K+]).
• During the experiment’s first hour, no treatment was administered.
• At the start of the second hour, either 0.5 mg of omeprazole per kg of body weight or a comparable volume of 0.9% sodium chloride solution was administered intravenously as a random bolus.
• A continuous intravenous infusion of pentagastrin started from the beginning of the third hour and lasted for two hours.

Research Findings

• The response to pentagastrin in horses treated with sodium chloride was consistent with prior studies—there was a significant decrease in pH and an increase in the volume of gastric contents.
• Sodium and potassium concentrations remained unchanged, while their respective outputs showed a minor increase that corresponded with the volume.
• Post-omeprazole treatment, the pH of the gastric contents increased substantially and stayed between 5 and 6 throughout pentagastrin infusion.
• The sodium concentration showed a significant rise after omeprazole treatment, closely mirroring the pH response for the rest of the experiment.
• The gastric content volume grew significantly in response to pentagastrin infusion, leading to a notable surge in sodium output.
• However, there was no change observed in potassium output after omeprazole treatment.

Conclusion

• Pentagastrin significantly stimulates a nonparietal secretory response in the gastric contents of cannulated horses.
• Despite pretreatment with omeprazole, the volume and sodium concentration of this response was maintained.
• The pH content became more basic, indicating that the nonparietal response isn’t mediated by an omeprazole-sensitive proton pump.