ExtractThe saliva of patients with cystic fibrosis of the pancreas (CFP) contains higher concentrations of sodium than the saliva of normal subjects. The hypothesis that the salivary electrolyte abnormality in CFP may be due to a sodium transport inhibitory factor (or factors) present in the saliva of the~e:~atients was investigated. Such a factor would decrease sodium reabsorption in the salivary glands and cause increased sodium concentrations in the final saliva. Retrograde perfusion of the rat parotid gland was used to determine this factor. Retrograde perfusion with normal saline or saliva from normal children did not affect the rate of sodium reabsorption in the rat parotid gland. Retrograde perfusion with ouabain containing saline or saliva from patients with CFP resulted in a marked decrease of the rate of sodium reabsorption. I t was concluded that saliva from patients with CFP contains a factor that causes inhibition of sodium transport in the rat parotid gland. The similarity of the effects of ouabain and saliva from patients with CFP led us to the investigation of the possibility of a common mode of action. I t was demonstrated that the saliva of patients had no effect on the in vitro activity of membrane ATPase preparations obtained from beef parotid, human erythrocytes and rat kidneys. This indicates that the saliva of patients with CFP causes inhibition of sodium reabsorption in the rat parotid by an action other than inhibition of the activity of ATPase, an enzyme known to be involved in sodium transport across biological membranes. Speculation

A factor inhibitory to sodium transport exists in the sweat of patients with cystic fibrosis of the pancreas. When the duct system of the rat parotid was perfused with sweat from patients, marked inhibition of sodium reabsorption was observed. Perfusion with sweat from normal subjects caused no change in sodium reabsorption. The factor thus demonstrated may be responsible for the increased sodium concentrations in the sweat of patients with cystic fibrosis.

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