<prompt> Which of the following drugs cause relaxation of LES? 1. Nitrates 2. Histamine blockers 3. Morphine 4. Atropine 5. Calcium channel blockers1,2 31,4 51,2 5All  <response>: Factor causing relaxation of LES Factor increasing LES pressure Pharmacological agents:nitrates, anticholinergics, barbiturates, calcium channel blockers, caffeine, theophylline, diazepam, dopamine, prostaglandin E1 and E2 and meperidine Pepperdine Chocolate Coffee Alcohol Smoking Fat Antacids Cholinergics Domperidone Metoclopramide Prostaglandin F2 Also know: LES pressure is higher in the supine position than in the upright position. Ref: Schwarz 9e, Page 812; Harrison 17e, Page 1741. 