Effect of the nitric oxide donor, glyceryl trinitrate, on humangall bladder motility

Background—Nitric oxide is a majorneurotransmitter in non-adrenergic, non-cholinergic (NANC) pathways.NANC inhibitory innervation has been shown in human gall bladder musclein vitro; the role of nitric oxide in human gall bladder emptyinghowever is undefined.
Aims—To study the effect of glyceryltrinitrate, a nitric oxide donor, on gall bladder emptying in healthysubjects using a randomised, double blind, crossover, placebocontrolled design.
Methods—Ultrasonographic gall bladdervolume was measured in the fasting state in eight healthy volunteersafter randomised administration of either glyceryl trinitrate 1200 µgbuccal spray or placebo spray. On two further occasions, afterrandomised administration of either glyceryl trinitrate 1200 µgbuccal spray or placebo spray, gall bladder volumes were also measuredafter a liquid test meal.
Results—Glyceryl trinitrate significantlyincreased fasting gall bladder volume to a mean of 114% (SEM 5%) ofpretreatment volume (p=0.039). Glyceryl trinitrate also significantlyimpaired gall bladder emptying between five and 40 minutespostprandially. Gall bladder ejection fraction was also reduced afterglyceryl trinitrate compared with placebo (43 (6.9)% versus 68.4 (6.5)%, p=0.016).
Conclusions—This study shows that glyceryltrinitrate produces gall bladder dilatation in the fasting state andreduces postprandial gall bladder emptying, suggesting that nitricoxide mechanisms may be operative in the human gall bladder in vivo.

Keywords:gall bladder motility; nitric oxide; glyceryltrinitrate