To determine the effect of intraesophageal high PCO2 solution as compared to acidic and saline solutions on subjects' heartburn sensation using stiumlus-response functions.

Presently, the exact mechanism of GERD and the role of CO2 in pathogenesis of heartburn symptoms is unclear. CO2 conversion to protons may play a key role in the mechanism for heartburn sensation. This is a prospective, randomized study that will help further explore the mechanism for heartburn sensation in GERD patients and can be a prelude for further studies examining the role of new class antireflux agents such as carbonic anhydrase inhibitors in the treatment of patients with heartburn.

Inclusion Criteria:

10 Healthy Controls

• Normal EGD, Normal 24-hr pH

• 18-80 Years of age

• Able to read, understand and complete study questionnaires and diary

• Able to understand study procedures and sign informed consent

• Albe to comply with all study requirements

  10 NERD (Non-Erosive Reflux Disease)

• 18-80 Years of age

• Willing to stop PPI/H2 Blocker prior to EGD

• Have heartburn symptoms 2+ times per week for at least 3 months.

Exclusion Criteria:

• Esophageal erosions, Barretts, or peptic stricture on EGD
• Previous esophageal, gastric or duodenal surgery
• underlying co-morbidities
• Diabetes mellitus (requires insulin), scleroderms, or neuromuscular disorder
• Upper airway symptoms
• Tricyclic antidepressants, antispasmodics, selective serotonin receptor inhibitors, thiazides, bile acid-binding agents or prokinetics
• Patients who cannot or are unwilling to sign ICF