Role of NAADP for calcium signaling in the salivary gland.

Coordination of intracellular Ca ²⁺ signaling in parotid acini is crucial for controlling the secretion of primary saliva. Previous work from our lab has demonstrated acidic-organelle Ca ²⁺ release as a participant in agonist-evoked signaling dynamics of the parotid acinar cell. Furthermore, results implicated a potential role for the potent Ca ²⁺ releasing second messenger NAADP in these events. The current study interrogated a direct role of NAADP for Ca ²⁺ signaling in the parotid salivary gland acinar cell. Use of live-cell Ca ²⁺ imaging, patch-clamp methods, and confocal microscopy revealed for the first time NAADP can evoke or enhance Ca ²⁺ dynamics in parotid acini. These results were compared with pancreatic acini, a morphologically similar cell type previously shown to display NAADP-dependent Ca ²⁺ signals. Findings presented here may be relevant in establishing new therapeutic targets for those suffering from xerostomia produced by hypofunctioning salivary glands.
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