AJP - Gastrointestinal and Liver Physiology, Vol 253, Issue 5 627-G630, Copyright © 1987 by American Physiological Society
Oxygen radicals stimulate guinea pig gallbladder glycoprotein secretion in vitro
W. B. Hale, B. Turner and J. T. LaMont
Evans Memorial Department of Clinical Research, University Hospital, Boston University School of Medicine, Massachusetts 02118.
In several animal models of cholelithiasis, and in humans with gallstones,
hypersecretion of gallbladder mucin is observed. This study was undertaken
to determine the effect of oxygen radicals on guinea pig gallbladder
glycoprotein secretion in organ culture. Mucosal explants were incubated
with [3H]glucosamine hydrochloride to label glycoproteins, then exposed to
oxygen radicals generated by chelated ferric iron and ascorbic acid. Marked
stimulation of glycoprotein release was observed after a 30-min exposure to
the oxygen radical-generating system, and the effect was inhibited by
mannitol. The stimulatory effect of hydroxyl radical was not accompanied by
leakage of intracellular lactate dehydrogenase. Parallel experiments with
human granulocytes activated with f-Met-Leu-Phe and coincubated with
gallbladder explants revealed similar results. These results indicate that
oxygen radicals, especially the hydroxyl radical (OH.), are capable of
stimulating rapid release of mucous-type glycoproteins from gallbladder
epithelium.
