Daniela Ecke

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In most epithelia ion transport is tightly regulated. One major primary target of such regulation is the modulation of ion channels. The present brief review focuses on one specific example of ion channel regulation by the cystic fibrosis transmembrane conductance regulator (CFTR). CFTR functions as a cAMP-regulated Cl- channel. Its defect leads to the(More)
Previously we have shown that mid crypt cells of corticoid treated rats possess an amiloride inhibitable Na+ conductance (NAC) and show an increased CI- conductance when stimulated by prosta-glandin or the second messenger cAMP. The NAC is supposed to determine the magnitude of NaCl absorption. The CI- conductance defines the magnitude of NaCI secretion. In(More)
Cl- secretion in the rat colonic crypt base cell (bc) requires the coordinated (a) opening of Cl- channels in the luminal membrane; (b) activation of the Na+2Cl-K+ cotransporter; (c) enhanced conductive K+ exit from the cell; and (d) increased pumping by the (Na+ + K+)-ATPase. In this study we focus on the importance of conductive K+ exit. After stimulation(More)
Whole-cell patch-clamp studies in base cells of isolated colonic crypts of rats pretreated with dexamethasone were performed to examine the effects of stimulation by forskolin (10 μmol/1). The experiments were designed in order to distinguish between two postulated effector mechanisms: the activation of a non-selective cation channel and the activation of(More)
Whole-cell patch-clamp studies were performed in isolated colonic crypts of rats pretreated with dexamethasone (6 mg/kg subcutaneously on 3 days consecutively prior to the experiment). The cells were divided into three categories according to their position along the crypt axis: surface cells (s.c.); mid-crypt cells (m.c.) and crypt base cells (b.c.). The(More)
Chromanols, which were recently shown to inhibit cAMP-mediated Cl- secretion in colon crypts via a blockade of a cAMP-activated K+ conductance, were analyzed for their effects on distinct cloned K+ channels expressed in Xenopus oocytes. The lead chromanol 293B specifically inhibited I(sK) channels with an IC50 of 7 micromol/l without affecting the delayed(More)
Activation of Cl− and K+ channels is necessary to drive ion secretion in epithelia. There is substantial evidence from previous reports that vesicular transport and exocytosis are involved in the regulation of ion channels. In the present study we examined the role of cytoskeletal elements and components of intracellular vesicle transport on ion channel(More)
The present study was performed to examine Ca2+-dependent and cell-swelling-induced ion conductances in a polarized bronchial epithelial cell line (16HBE14o-). Whole-cell currents were measured in fast and slow whole-cell patch-clamp experiments in cells grown either on filters or on coated plastic dishes. In addition the transepithelial voltage (V te) and(More)
 Glucocorticoids, such as dexamethasone, induce amiloride-sensitive Na+ conductances in rat distal colon epithelium. The activity of these conductances diminishes from the surface to the base of the crypt whereas cAMP-stimulated Cl–secretion decreases from the crypt base to the surface. These gradients are likely to be perturbed during carcinogenesis. We(More)
 Rats injected with dimethylhydrazine for 5 weeks (DMH, 40 mg/kg body weight) invariably develop colonic cancer after a latency of some 10–14 weeks. Preliminary studies have suggested that Na+ absorption by surface colonic crypt cells is attenuated in the preneoplastic period (8–12 weeks after the first injection of DMH). The present study of(More)