High-affinity binding sites for gastrin on isolated rabbit gastric mucosal cells

Area of Science:

• Gastroenterology
• Endocrinology
• Molecular Biology

Background:

• Gastrin is a key hormone regulating gastric acid secretion.
• Understanding gastrin's cellular interactions is crucial for gastrointestinal research.

Purpose of the Study:

• To investigate the specific binding of a gastrin analogue to isolated rabbit gastric mucosal cells.
• To characterize the binding sites and their affinity for the gastrin analogue.

Main Methods:

• Utilized a radiolabeled gastrin analogue, [125I](Nle11)-HG-13, for binding assays.
• Performed experiments on isolated rabbit gastric mucosal cells at varying temperatures and with different competing ligands.
• Determined dissociation constants (Kd) and assessed the reversibility and specificity of binding.

Main Results:

• Identified specific, saturable binding sites for [125I](Nle11)-HG-13 on rabbit gastric mucosal cells with a Kd of 70 pM.
• Observed increased binding with higher incubation temperatures (4°C to 37°C).
• Demonstrated that gastrin analogues, CCK-7, and gastrin antagonists inhibited binding, while other hormones and neurotransmitters did not.

Conclusions:

• Isolated rabbit gastric fundic mucosal cells possess high-affinity binding sites for the gastrin analogue (Nle11)-HG-13.
• These binding sites exhibit specificity for gastrin and related peptides.
• The findings support the existence of distinct gastrin receptors on gastric mucosal cells.