Structure-Function Studies of Agonists and Antagonists for Gastrointestinal Peptide Receptors on Pancreatic Acinar Cells

Abstract

With the development of techniques to prepare dispersed pancreatic acini that respond to secretagogues, it became possible to investigate the cellular basis of action of the various peptides that stimulate pancreatic enzyme secretion. Various peptides differed in efficacy, potency, and configuration of their dose-response curves for stimulating enzyme secretion (Fig. 1). Pancreatic acini have receptors for different secretagogues, and with the development of techniques to prepare biologically active radiolabeled ligands for each group of structurally similar peptides, the existence of multiple classes of receptors was demonstrated directly (Fig. 2). Figure 2 summarizes the seven different classes of receptors that mediate the action of various secretagogues on pancreatic acini. Also summarized in Fig. 2 is the biochemical basis of action of each of these different receptors.