AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 3 287-G292, Copyright © 1986 by American Physiological Society
Production and secretion of intrinsic factor by isolated rabbit gastric mucosa
D. Serfilippi and R. M. Donaldson Jr
During 24 h of organ culture, rabbit gastric fundic mucosal explants
maintain constant tissue levels of intrinsic factor (IF) while steadily
secreting this glycoprotein into culture medium. Mucosal explants thus
generate in one day an average of 1.8 pmol of new IF per milligram mucosal
protein, an amount corresponding to 70% of IF present in explant tissue.
Cultured explants also incorporate [35S]methionine into tissue IF and
secreted IF at a constant rate. Histamine combined with
isobutylmethylxanthine stimulates explants to release IF into the culture
medium, but tissue levels of IF are diminished and specific activities of
tissue and secreted IF remain the same. Fluorograms of 35S-labeled proteins
generated by cultured explants fail to show cobalamin-binding precursors or
breakdown products of IF. These findings complement previous morphological
documentation of IF synthesis by gastric mucosa. Histamine appears to
stimulate IF secretion without altering IF synthesis.
