Gastrin receptors on isolated canine parietal cells

Area of Science:

• Gastroenterology
• Cell Biology
• Endocrinology

Background:

• Gastrin stimulates gastric acid secretion, but the specific receptors involved in the fundic mucosa are not fully characterized.
• Understanding these receptors is key to comprehending the regulation of gastric acid production.

Purpose of the Study:

• To identify and characterize the receptors in the canine fundic mucosa responsible for mediating gastrin-stimulated acid secretion.
• To determine the cellular localization of these gastrin receptors.

Main Methods:

• Enzyme-dispersed canine fundic mucosal cells were used.
• Synthetic iodinated gastrin ([Leu15]-G17) was employed for binding studies.
• Cell separation techniques including elutriation and density gradients were utilized.
• Parietal cell function was assessed by [14C]aminopyrine accumulation.

Main Results:

• Specific, saturable binding of iodinated gastrin ([Leu15]-G17) was observed on canine fundic mucosal cells.
• Gastrin binding strongly correlated with parietal cell distribution.
• Gastrin receptors were undetectable on chief cells but present on other smaller mucosal cells.
• Gastrin and cholecystokinin octapeptide were equipotent in binding and stimulating parietal cell function.
• Proglumide inhibited gastrin binding and parietal cell stimulation.

Conclusions:

• Canine parietal cells possess specific gastrin receptors that mediate the stimulation of acid secretion.
• These receptors are not found on chief cells, suggesting a specialized role in acid production.
• The presence of gastrin binding on other smaller mucosal cells warrants further investigation.