CFTR and outward rectifying chloride channels are distinct proteins with a regulatory relationship

Article Abstract:

The regulation of outward rectifying chloride channels (ORCC) in the presence or absence of the cystic fibrosis transmembrane conductance regulator (CFTR) was examined using studies of ORCC incidence in cells from normal and CFTR (-/-) mice. ORCC were found to be present in the nasal epithelial cells of CFTR (-/-) mice, indicating that they did not originate from the CFTR molecule. In addition, protein kinase A was found to regulate ORCC in membrane patches obtained from normal cells, a result not found in CFTR (-/-) cells. These results show that CFTR regulates another protein.

Biological transport, Active, Active biological transport, Physiological regulation, Protein metabolism, Chloride channels

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Activation of the epithelial Na+ channel (ENaC) requires CFTR Cl- channel function

Article Abstract:

Epithelial Na+ channel (ENaC) function depends critically on the state of a specific Cl- channel, the CFTR channel, in a purely salt-absorbing epithelium. It has also been established that ENaC cannot be activated in cystic fibrosis ducts where CFTR is faulty or absent. Reduced salt absorption in cystic fibrosis is the result of both poor Cl- conductance and poor Na+ conductance. A loss of secretory transport could lead to an apparently larger Na+ absorption in cystic fibrosis airway tissue.

Sodium channels

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Membrane-restricted regulation of Ca2+ release and influx in polarized epithelia

Article Abstract:

A study conducted on polarized human nasal epithelial (HNE) cells shows that the release of intracellular Ca2+ is controlled by the stimulation of the P2 purinoceptors on the ipsilateral membrane. Treatment of HNE with ATP stimulates the P2 receptors, which are linked to phospholipase C, on the ipsilateral but not on the contralateral side of the membrane. The results suggest that the release of Ca2+ in response to receptor stimulation is not controlled by inositol (1,4,5) trisphosphate.

Observations, Epithelial cells, Calcium in the body, Calcium (Nutrient), Membranes (Biology)

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