Increases in cellular calcium concentration stimulate pepsinogen secretion from dispersed chief cells

Area of Science:

• Gastroenterology
• Cell Physiology
• Biochemistry

Background:

• Pepsinogen secretion is a critical function of gastric chief cells.
• The role of intracellular calcium concentration ([Ca]i) in regulating this secretion requires further elucidation.

Purpose of the Study:

• To investigate the relationship between intracellular calcium concentration ([Ca]i) and pepsinogen secretion in guinea pig gastric chief cells.
• To evaluate a novel, highly sensitive assay for measuring pepsinogen secretion.

Main Methods:

• Dispersed guinea pig gastric chief cells were utilized.
• Intracellular calcium concentration ([Ca]i) was measured using the fluorescent probe quin2.
• Pepsinogen secretion was quantified using a new, highly sensitive 125I-albumin substrate assay.
• Cells were stimulated with calcium ionophores to induce changes in [Ca]i and secretion.

Main Results:

• Basal intracellular calcium concentration ([Ca]i) was determined to be 105 +/- 4 nM.
• The novel pepsinogen assay demonstrated 1000-fold greater sensitivity compared to spectrophotometric methods.
• Ionophore-induced changes in [Ca]i and pepsinogen secretion exhibited similar kinetics and stoichiometry.

Conclusions:

• The study provides strong evidence supporting calcium as a crucial cellular mediator of pepsinogen secretion.
• The developed 125I-albumin assay offers a significant advancement in measuring pepsinogen secretion due to its sensitivity and practicality.