C-type natriuretic peptide enhances amylase release through NPR-C receptors in the exocrine pancreas.

SABBATINI M; RODRIGUEZ M; DI CARLO MB; DAVIO C; VATTA MS; BIANCIOTTI LG

AMERICAN JOURNAL OF PHYSIOLOGY-GASTROINTESTINAL AND LIVER PHYSIOLOGY

American Physiological Society

Lugar: Bethesda; Año: 2007 vol. 293 p. 987 - 994

0193-1857

Several studies show that C-type natriuretic peptide (CNP) has a modulatory role in the digestive system. CNP administration reduces both jejunal fluid and bile secretion in the rat. In the present study we evaluated the effect of CNP on amylase release in isolated pancreatic acini as well as the receptors and intracellular pathways involved. Results showed that all natriuretic peptide receptors were expressed not only in the whole pancreas but also in isolated pancreatic acini. CNP stimulated amylase secretion with a concentration-dependent biphasic response; maximum release was observed at 1pM CNP whereas higher concentrations gradually attenuated it. The response was mimicked by a selective NPR-C agonist, and inhibited by pertussis toxin, strongly supporting NPR-C receptor activation. CNP-evoked amylase release was abolished by U-73122 (PLC inhibitor) and 2-APB (IP3 receptor antagonist), partially inhibited by GF-109203X (PKC inhibitor) and unaltered by ryanodine or PKA and PKG inhibitors. Phosphoinositide hydrolysis was enhanced by CNP at all concentrations and abolished by U-73122. At 1 and 10 pM CNP did not affect cAMP or cGMP levels, but at higher concentrations it increased cGMP and diminished cAMP content. Present findings show that CNP stimulated amylase release through the activation of NPR-C receptors coupled to the PLC pathway and downstream effectors involved in exocytosis. The attenuation of amylase release was likely related to both cAMP reduction and cGMP increase. The augment in cGMP supports activation of NPR-A/NPR-B receptors probably involved in calcium influx. Present findings give evidence that CNP is a potential direct regulator of pancreatic function.