PACAP-38 causes phospholipase C-dependent calcium signaling in rat acinar cell line.

Abstract

Pituitary adenylate cyclase activating peptide (PACAP-38), a neuropeptide of the vasoactive intestinal peptide/secretin family, localizes to intrapancreatic neurons and stimulates exocrine secretion from the pancreas. PACAP-38 stimulates calcium signaling in the rat pancreatic cell line AR42J. The purpose of this study was to elucidate the mechanisms of PACAP-evoked calcium signaling in these cells. Continuous measurements of intracellular calcium were taken by fluorescent digital microscopy with the dye fura-2. Mechanisms of PACAP-38-evoked calcium signals were determined by a panel of inhibitors. Inositol phosphates production in response to PACAP-38 was measured. The ability of PACAP-38 to stimulate amylase release was used to determine a relevant dose range for these studies. We have shown that (1) AR42J cells respond to PACAP-38 with biphasic increases in [Ca2+]i in a dose-dependent fashion; (2) PACAP-38 acts through phospholipase C to release inositol triphosphate (IP3)-sensitive Ca2+ stores with (3) a subsequent influx of extracellular Ca2+. PACAP-38 activates calcium signaling through phospholipase C at concentrations that stimulate amylase release in AR42J cells.