The extracellular pH, sodium and divalent cation concentrations influence the ATP-induced changes in cytosolic Ca(2+) concentration ([Ca(2+)](i)). This elevation of [Ca(2+)](i) and activation of Ca(2+)-dependent Cl(-) channels represent a possible therapeutic approach in cystic fibrosis (CF). We investigated the changes of [Ca(2+)](i) in different external ionic environment, and P2X purinergic receptors (P2XRs) expression in the control and CF airway epithelial cells. The parallel removal of Na(+) and alkalinization of the extracellular solution increased the amplitude of sustained ATP-induced Ca(2+) signals independent of wild-type or mutant CFTR expression. The ATP-induced Ca(2+) entry was either inhibited or stimulated by Zn(2+) depending on the extracellular Na(+) concentration. In Na(+)-free environment, Zn(2+) and other divalent cations elicited a biphasic Ca(2+) signal. Immunohistochemical data suggest that, multiple subtypes of P2XRs are expressed in these airway epithelial cells. In conclusion, Ca(2+) entry is finely regulated by external ionic environment. Therefore, we speculate that properly compiled aerosols could influence efficacy of zinc-based therapy in CF.Copyright 2009 Elsevier B.V. All rights reserved.
![Hexanoic acid, 6-(acetyloxy)-2,3,3a,4,5,6,6a,7,8,9b-decahydro-3, 3a-dihydroxy-3,6, 9-trimethyl-8-[(2-methyl-1-oxo-2-butenyl)oxy]-2-oxo-4-(1-oxobutoxy )azuleno[4,5-b]furan-7-yl ester, [3R-[3.alpha.,3a. Structure](http://hg.y866.cn/chemical/lib/image/caspic/106/67526-94-7.png)