Effect of sodium ions on cyclic AMP and cyclic GMP levels in mouse parotid acini

The ability of the β-adrenergic agonist, isoproterenol, to elevate intracellular levels of cyclic-AMP (c-AMP) and cyclic GMP (c-GMP) in mouse parotid acini was dependent upon the extracellular sodium concentration. In the absence of extracellular sodium isoproterenol-stimulated c-GMP and c-AMP levels were significantly reduced; carbachol-stimulated c-GMP levels were not affected. Monensin, a sodium ionophore, mimicked the effects of isoproterenol in elevating c-GMP levels; this effect was abolished in the absence of extracellular sodium. Monensin did not mimic the effects of isoproterenol in elevating c-AMP levels. The data presented suggests that sodium ions may play a role in β-adrenergic regulation of cyclic nucleotide levels in mouse parotid gland and that the mechanisms involved in regulation of c-AMP and c-GMP levels appear to be different.