Cellular physiology and biochemistry : international journal of experimental cellular physiology, biochemistry, and pharmacology
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Cell. Physiol. Biochem. · Jan 2001
Effects of the serine/threonine kinase SGK1 on the epithelial Na(+) channel (ENaC) and CFTR: implications for cystic fibrosis.
Cystic fibrosis (CF) is characterized by impaired Cl(-) secretion and increased Na(+) reabsorption in several tissues including respiratory epithelium. Many CFTR mutations have been identified over the past years. However, only a poor correlation between the genotype and lung phenotype was found suggesting additional factors influencing the phenotype and course of the disease. ⋯ Lung tissue from CF patients strongly expressed the serine/threonine kinase h-sgk1 which was not the case for non-CF lung tissue. Loss of CFTR function itself in a CF lung epithelial cell line did not increase SGK1 expression. In summary, enhanced expression of h-SGK1 in epithelial cells of CF-lung tissue may be a novel pathophysiological factor contributing to increased Na(+) channel activity and thus to increased Na(+) transport in CF.
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Cell. Physiol. Biochem. · Jan 2001
Hypoxia-effects on Ca(i)-signaling and ion transport activity of lung alveolar epithelial cells.
In excitatory cells specific responses upon changes in PO(2) are mediated by changes in intracellular Ca (Ca(i)). We wanted to know whether ion transport of lung alveolar epithelial cells is regulated by Ca(i) and whether Ca(i) and Ca(i) -signaling are affected by hypoxia in a way that might explain hypoxic transport inhibition (Mairbäurl et al. AJP 273: L797, 1997). ⋯ These results indicate that ion transport of alveolar epithelial cells is modulated by Ca(i). A change in Ca(i) does not mediate hypoxic transport inhibition. The decreased Ca(i) transients in hypoxia might indicate a blunted response to extracellular stimuli.