Alterations in gastric mucus secretion in rhesus monkeys after exposure to ionizing radiation.

The aim of the present study was to evaluate the effect of gamma-irradiation on soluble gastric mucus. Six conscious chair-adapted rhesus monkeys were studied once before and twice after exposure to ionizing irradiation (800 rads). Using a marker (99mTc-DTPA) dilution technique, acidic glycoprotein (AG), neutral glycoprotein (NG), ion, and fluid output were determined during a basal period and after the administration of an 80-ml water load. Irradiation significantly increased the outputs of both AG and NG during the basal period. After the water load, NG output remained elevated but irradiation abolished postload AG output thus inhibiting the normal rise in AG output stimulated by the load. Two days after irradiation NG output had returned to control levels whereas AG output was still suppressed. Sodium and potassium ion outputs were unaltered by irradiation. Chloride and fluid outputs were significantly inhibited on the day of irradiation but had returned to control levels within 3 days. These results indicate that irradiation produces significant changes in both the quantity and nature of the soluble mucus glycoproteins secreted into the gastric juice. It is suggested that these changes may compromise the protective ability of gastric mucus.