CAMP STIMULATED SWEAT RATE IN CYSTIC FIBROSIS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is the development of a cyclic-AMP(cAMP)-stimulated "sweat rate" test that will discriminate between fully functional, partially functional, and non-functional forms of the Cystic Fibrosis Transmembrane Conductance Regulator(CFTR). Sweat production can be stimulated by both cholinergic & adrenergic agonists. Collection of cholinergic stimulated sweat & the subsequent measurement of sweat chloride concentration is the basis of a standard diagnostic test for cystic fibrosis (CF), the pilocarpine iontophoresis sweat test. Stimulation of sweat production with pilocarpine leads to initial production of an isotonic secretion in the sweat gland. In non-CF patients, as the secretion traverses the sweat duct, chloride is reabsorbed leading to low concentrations of chloride in sweat as it appears on the skin. This chloride resorption is dependent on the presence of functional CFTR. In CF patients, who lack functional CFTR, the sweat chloride concentration remains high, & distinguishes most, but not all, CF from non-CF patients. However, this technique does not distinguish heterozygote carriers of CFTR mutations from non-carriers, nor does the sweat chloride concentration correlate with disease severity. The hypothesis is that measurement of cAMP-mediated sweat rates will distinguish among CF subjects, non-CF subjects, and non-affected carriers of CFTR mutations. A secondary hypothesis is that there will be a correlation between CFTR activity and sweat rate such that non-affected carriers of CFTR mutations will have intermediate sweat rates to CF and non-CF control subjects. Another secondary hypothesis is that different classes of CFTR mutations can be associated with different levels of sweat rate. Subjects of both genders and all ages are eligible for entry.