Effect of pyloric blockade and infusion of histamine or pentagastrin on gastric secretion in horses.

The study investigated the origin of non-acid gastric secretions in horses using pyrilamine, saline, pentagastrin, or histamine under two different duodenal conditions. The results showed that the non-acid secretions collected during IV infusion of pentagastrin originated from the duodenum, suggesting a possible link to the development of ulcers in horses.

Research Methodology

• The study used a Latin square design with 6 horses and 3 types of treatments, and examined two specific duodenal conditions (with a balloon obstructing the pylorus [B condition] or without balloon, allowing the stomach and duodenum contents to mix [NB condition]).
• Each horse had a gastric cannula (an implanted tube for sampling) and a duodenal catheter (a tube inserted into the duodenum) for ease of experimentation and collection of needed fluids.
• Gastric and duodenal content samples were collected at 15-minute intervals for analysis.
• The experiment had several phases which included a baseline measurement, an IV infusion of pyrilamine maleate, another with untreated condition, and IV infusion of saline solution alone, saline solution with pentagastrin and saline solution containing histamine.
• Different measurements were taken such as the volume of the samples and the electrolyte concentrations.

Results of the Study

• The experiment revealed that both pentagastrin and histamine stimulated the maximum production of acid in the horse’s stomach, but the concentration of hydrogen ions induced by pentagastrin was notably less during NB conditions as compared to histamine infusion or pentagastrin infusion during B conditions.
• It was also observed that a large volume secretion, accompanied by increased sodium ion output, was produced in response to pentagastrin during NB conditions. This amount exceeded that produced in B conditions, and both figures were significantly larger than values produced during histamine infusion in both B and NB conditions.

Conclusions

• The researchers concluded that the non-acidic secretions obtained during IV infusion of pentagastrin originated from the duodenum, not the stomach.
• It was also found that pentagastrin increased the reflux of duodenal contents into the stomach.
• The team proposed that the movement of duodenal contents into the stomach has implications for the formation of ulcers in horses. This could form the basis for future studies into the prevention and treatment of equine ulcers.