The investigators hypothesize that measurement of beta adrenergic induced sweat rate using an evaporimeter can accurately and reliably determine different levels of CFTR dysfunction within a spectrum of patients expressing various degrees of cystic fibrosis disease.

The investigators overall goal is to determine whether the evaporimeter technique of measuring beta-adrenergic induced sweat rate is capable of accurately and reliably identifying different levels of CFTR dysfunction, as a prerequisite before advancing this technique as biomarker assay into clinical trials.

Preliminary data show that following β-adrenergic stimulation, evaporimetry can reliably measure sweat secretion that is: highly reproducible in healthy controls; reduced by 50% in CF obligate heterozygotes; and absent in CF patients carrying severe mutations on both alleles. Further, test- retest experiments suggest good intra-individual reliability. All these features satisfy the required criteria for a biomarker assay that is capable of assessing small increments in CFTR function in vivo in clinical trials designed to assess the effectiveness of correctors and potentiators of CFTR channel activity. Therefore, to provide additional evidence of the value of this novel technique the investigators will determine the accuracy and reliability of evaporimetry to measure Beta-adrenergic induced sweating in subjects with a range of CFTR channel activity.

Inclusion Criteria:

1. Male or female ages 18 years and older.
2. Subject with or without confirmed diagnosis of CF.
3. Written informed consent obtained from subject.

Exclusion Criteria:

1. Patients who are participating in clinical trials evaluating the safety, efficacy or clinical outcome of drugs that may alter the CFTR Cl channel function will be excluded.
2. Any subject with a known hypersensitivity to any agonist used in the study or subjects receiving any drug (e.g. theophylline, antihypertensive agent) that might interfere with the investigations.
3. Subjects with active dermatitis or other chronic skin condition such as psoriasis or a strong allergic history.
4. Patients with a history of cardiac disease (including arrhythmias or hypertrophic obstructive cardiomyopathy).
5. CF patients with severe malnutrition (BMI<18 kg/m2).
6. CF patients with severe lung disease (FEV1<25%).
7. Subject who has been treated for pulmonary exacerbation or other acute illness within one week of the study procedure.
8. Any medical condition that, in the opinion of the investigator, will interfere with accurate conduct of the study.
9. Subjects who are pregnant or lactating.
10. Subject who is not able to stop inhalation therapy of β -adrenergic drugs 12 hrs before starting each test.