Topical glyceryl trinitrate relaxes the sphincter of Oddi.

BACKGROUND/AIM Nitric oxide (NO) may be involved in non-adrenergic non-cholinergic (NANC) inhibitory innervation of the sphincter of Oddi (SO). The effects of topical application of glyceryl trinitrate (GTN), a NO donor, upon SO motility were examined. METHODS Nineteen patients undergoing routine SO manometry for investigation of abdominal pain were studied. After routine recording of SO motility, they were randomised into three groups to receive 10 ml of normal saline, 5 mg GTN (0.5 mg/ml) or 10 mg (1 mg/ml) GTN. Drug solutions were infused topically onto papilla via the manometry catheter and recordings were continued for a further 5 minutes. RESULTS There was no significant change in SO motor variables following application of normal saline. GTN reduced SO tonic and phasic contractions. In four patients, there was complete abolition of all phasic contraction. CONCLUSIONS Local application of GTN inhibits SO motility. This may have application for diagnostic and therapeutic biliary endoscopy.