Histamine-induced gastric acid secretion in horses.

The research examined how histamine, a compound involved in local immune responses, influences gastric acid production in horses. It identified the dose of histamine required to stimulate maximum gastric secretion and explored its potential role in gastric diseases such as peptic ulcers.

Research Methodology

• The study involved six adult horses fitted with gastric cannulae – tubes inserted into the stomach to enable fluid collection.
• Gastric content was collected every 15 minutes, and various parameters such as volume, pH, hydrogen ion concentration and output, and sodium concentration and output were observed.
• Horses were observed under various conditions – without any treatment (baseline), after injection with pyrilamine maleate (an antihistamine), and during one-hour infusions with three different concentrations of histamine.

Key Findings

• The volume, hydrogen ion concentration, and hydrogen ion output of the horses’ gastric contents significantly increased during histamine infusion when compared to baseline values.
• The effects were most evident during histamine infusion at rates of 15 or 30 microg/kg/h, indicating that these doses were optimal for stimulating gastric secretion in horses.
• Meanwhile, sodium concentration significantly decreased during histamine infusion, though sodium output remained unchanged.

Conclusions and Implications

• The study concluded that histamine doses of 15 and 30 microg/kg/h stimulated maximal gastric secretion in horses.
• It also found that histamine mainly induced parietal secretion – the secretion of gastric acid by the stomach’s parietal (or oxyntic) cells.
• This research aids our understanding of how histamine influences gastric physiology in horses, providing valuable insights into the pathogenesis of conditions like peptic ulcer disease.