Effect of SNI-2011 on amylase secretion from parotid tissue in rats and in neuronal nitric oxide synthase knockout mice

Abstract The effect of (±) cis -2-methylspilo(1,3-oxathiolane-5,3′)quinuclidine (SNI-2011) on the secretory pathway of amylase in parotid tissues was investigated. SNI-2011-induced exocytosis was inhibited by a cell-permeable Ca 2+ chelator or inhibitors of calmodulin kinase II, neuronal nitric oxide synthase (nNOS), soluble guanyl cyclase, cyclic GMP-dependent protein kinase (PKG), and myosin light chain kinase, suggesting that these enzymes were coupled with the exocytosis. Stimulation with SNI-2011 of isolated rat parotid acinar cells loaded with 4,5-diaminofluorescein/diacetate (DAF-2/DA) induced a fast increase in DAF fluorescence corresponding to an increase in the NO production. SNI-2011-induced amylase secretion from parotid tissues in nNOS knockout mice has not been observed yet in spite of the expression of muscarinic M 3 receptors and the maintenance of secretory response to isoproterenol in the tissues. These results indicate the implication of the activation of Ca 2+ - and calmodulin-dependent enzymes and NOS-PKG signaling pathway in SNI-2011-induced amylase secretion from parotid acinar cells.