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Ion transport across Xenopus alveolar epithelium is regulated by extracellular ATP, UTP and adenosine

2003; Elsevier BV; Volume: 139; Issue: 2 Linguagem: Inglês

10.1016/j.resp.2003.09.007

1878-1519

Martin Fronius, Andreas Berk, Wolfgang Clauß, M. Schnizler,

Neuroscience of respiration and sleep

Native alveolar epithelium from Xenopus lung was used for electrophysiological Ussing chamber experiments to investigate ion transport regulation. The tissue exhibits a considerable absorption of Na+ ions and this transepithelial transport is largely up-regulated after treatment of donor animals with ACTH. Extracellular ATP, UTP and adenosine were tested for their regulating effects and all three increased Isc, which was mainly due to a stimulation of amiloride sensitive Na+ transport (increase of Iami 32% for ATP, 21% for UTP, 25% for adenosine). Solely the effect of UTP was completely abolished in the presence of amiloride. In contrast, the effects of ATP or adenosine disappeared under Cl−-free conditions. ATP and UTP proved to have additive effects and pyridoxalphosphate-6-azophenyl-2′,4′-disulfonic acid (PPADS), an antagonist of purinergic receptors, inhibited selectively the effect of UTP on Isc. Further, Isc was increased by the P2X selective agonist β,γ-meATP. We were able to demonstrate, that extracellular purines and pyrimidines play a possible role as auto/paracrine messengers for alveolar ion transport regulation in Xenopus lung.