In cystic fibrosis, administering saline to the nasal epithelium results in which change in transepithelial potential difference?

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Multiple Choice

In cystic fibrosis, administering saline to the nasal epithelium results in which change in transepithelial potential difference?

Transepithelial potential difference reflects the balance of ion movements across the nasal epithelium. In cystic fibrosis, Cl- secretion is impaired because CFTR is nonfunctional, so Na+ absorption via ENaC becomes relatively dominant. When saline is applied to the nasal surface, more Na+ is available to be absorbed, and with ENaC activity elevated, more positive charges move from the lumen into the tissue. This loss of positive charge from the lumen makes the luminal side more negative relative to the basolateral side, so the transepithelial potential difference becomes more negative. Hence, administering saline in CF tends to increase the negativity of the transepithelial potential difference.

Transepithelial potential difference reflects the balance of ion movements across the nasal epithelium. In cystic fibrosis, Cl- secretion is impaired because CFTR is nonfunctional, so Na+ absorption via ENaC becomes relatively dominant. When saline is applied to the nasal surface, more Na+ is available to be absorbed, and with ENaC activity elevated, more positive charges move from the lumen into the tissue. This loss of positive charge from the lumen makes the luminal side more negative relative to the basolateral side, so the transepithelial potential difference becomes more negative. Hence, administering saline in CF tends to increase the negativity of the transepithelial potential difference.

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