pH of sweat of patients with cystic fibrosis

pH of the sweat from patients with cystic fibrosis and in controls was measured as a function of the sweat-rate using a fluorescence-pH-indicator (umbelliferone). In both populations sweat is acid at low sweat-rates and alkaline at high ones. The results do not favour an abnormality of the ductal H+-secretion as the pathomechanism of cystic fibrosis.