Effects of AIF(4)(-) and ATP on intracellular calcium dynamics of crypt epithelial cells in mouse small intestine

Previous digital imaging analysis of intracellular calcium ion ([Ca2+](i)) dynamics in the crypt of the small intestine showed little response by most columnar cells to cholinergic and adrenergic agonists. The objective of th e present study was to demonstrate whether G-protein activators and other t ransmitters elicit [Ca2+](i) changes in crypt cells. We used digital imagin g to analyze spatiotemporal dynamics of [Ca2+](i) in Fura-2/AM-loaded isola ted crypts of mouse duodenum and ileum. AlF4- increased [Ca2+](i) in crypt columnar cells. In many cases, we observed [Ca2+](i) oscillations, which we re synchronized throughout the entire crypt. The oscillations were blocked by octanol. ATP, but not adenosine, caused a [Ca2+](i) increase in middle c rypt-regions of the duodenum and upper regions of the ileum, and the [Ca2+] (i) wave propagated towards the crypt bottom. The ATP-induced [Ca2+](i) inc rease was prevented by pretreatment with thapsigargin or suramin, but not b y La3+ or an extracellular Ca2+-free environment. Neither dopamine, 5-hydro xytryptamine (5-HT), histamine, vasoactive intestinal peptide, substance P, cholera toxin, nor guanylin had significant effects. The [Ca2+](i) dynamic s of Paneth cells were independent of the AlF4--induced synchronous oscilla tions of columnar cells and of the ATP-induced [Ca2+](i) wave. In conclusio n, crypt columnar cells have [Ca2+](i)-dependent intracellular signaling me chanisms that are linked with G proteins, and by which the cells communicat e with each other. ATP elicited [Ca2+](i) mobilization from columnar cells via P2 receptors, although some regional differences were noted between the duodenum and ileum.