Study to Investigate Prucalopride vs. Polyethylene Glycol 3350 on Colon Activity

Inclusion Criteria: * Chronic constipation * Male or female ages 18-75 years * Non-pregnant, non-lactating female Exclusion Criteria: * Drug-induced constipation * Subjects suffering from secondary causes of chronic constipation, such as: * Endocrine disorders, e.g. hypopituitarism, hypothyroidism, hypercalcemia, pseudohypoparathyroidism, pheochromocytoma or glucagon-producing tumors, unless these are controlled by appropriate medical therapy. * Metabolic disorders, e.g. porphyria, uremia, hypokalemia or amyloid neuropathy, unless these are controlled by appropriate medical therapy * Neurological disorders, e.g. Parkinson's disease, cerebral tumors, cerebrovascular accidents, multiple sclerosis, meningocele, aganglionosis, hypoganglionosis, hyperganglionosis, autonomic neuropathy or neuropathy due to chemotherapy, spinal cord injury, Chaga's disease, or major depression * Surgery. * Subjects with insulin-dependent diabetes mellitus * Rectal evacuation disorder/outlet obstruction * Subjects with intestinal perforation or obstruction * Severe renal impairment * Subjects with a history of alcohol or drug abuse * Subjects with lactose intolerance * Subjects with clinically significant cardiac, vascular, liver, pulmonary, endocrine, neurological or psychiatric disorders