CYSTIC FIBROSIS: A DISORDER OFCALCIUM-STIMULATED SECRETION AND TRANSEPITHELIAL SODIUM TRANSPORT?

Both increased epithelial reabsorption of sodium and raised intracellular calcium have been implicated in the pathogenesis of cystic fibrosis. An intracellular calcium-stimulated increase in sodium reabsorption through an amiloride-sensitive pathway and the consequent obligatory reabsorption of water could explain the thick tenacious secretions that characterise the disease. In the pancreatic ducts and airways increased intracellular calcium could exacerbate the problem of hyperviscous blockage by inducing acinar hypersecretion. Hypersecretion by the salivary and sweat glands would lead to excessive release of a factor which blocks sodium reabsorption by the cells in the ducts of these glands; this would lead to raised ion concentrations in sweat and saliva.