Structure and Function of the Gastro-esophageal Junction

Inclusion criteria: Study #1: * healthy male and female volunteers * aged at least 18 and not more than 49 y * no history of gastrointestinal symptoms * able to communicate well with the investigators and to comply with the requirements for the entire study * who provided written informed consent before participating in the study, after being given a full description of the trail. Study #2 and #3: * male and female patients with mild to moderate gastro-oesophageal reflux disease defined by presence of (1) reflux symptoms (2) pathological esophageal acid exposure between 5-10% on 24 hour ambulatory testing * aged at least 18 and not more than 49 y * no history of gastrointestinal symptoms * able to communicate well with the investigators and to comply with the requirements for the entire study * who provided written informed consent before participating in the study, after being given a full description of the trail. Exclusion criteria: * with present psychiatric disorders or mental impairment limiting the ability to comply with study requirements * with use of medications influencing upper GI motility within one week of the study (i.e. beta- blocker, calcium channel blockers, nitrates, prokinetic drugs, macrolide antibiotics) * with regular intake of medication; occasional use of analgesic e.g. aspirin, paracetamol is allowed * with symptoms or a history of gastrointestinal disease other than gastro-esophageal reflux disease (in study #2 and #3) * suffering from known liver, kidney, cardiovascular, neurological or pulmonary disease * with any evidence of infectious disease * with evidence or history of drug or alcohol abuse * with insufficient knowledge of the German language • who, for any reason, are unable to complete the study