In vitroabsorption of γ-globulin by neonatal intestinal epithelium of the pig

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Abstract
Anin vitro method, using fluorescent [gamma]-globulin and everted neonatal pig''s intestinal slices, for the study of the active transport of large molecules is described. Uptake of [gamma]-globulin occurred within 15 min. and required no exogenous substrates. In vitro absorption of [gamma]-globulin by intestinal epithelium was limited to the neonatal pig and 5-day-old mouse. No uptake was seen in intestines from a mature mouse, a pig with diarrhea, a normal pig, a mature rabbit, a guinea-pig, a chick, and a chick embryo. Chick embryo yolk sac readily took up [gamma]-globulin. Rings of everted intestinal epithelium remained active (still absorbed [gamma]-globulin) after incubating for 4-6 hr. in balanced salt solution (BSS). Uptake of [gamma]-globulin required oxygen and Na and was reversibly inhibited by metabolic antagonists such as iodoacetate, arsenate, fluoride, 4,6-dinitro-[PHI]-cresol, phlor-rhizin, anaerobiosis and cold. Under the conditions of the test, large colloidal molecules did not inhibit uptake of [gamma]-globulin. Similar results (although not as clear-cut) with metabolic inhibitors were obtained with preparations of chick embryo yolk sacs. Injuring mature pig''s intestinal epithelium with surface-active agents did not produce non-specific absorption artifacts that resembled the specific absorption found in immature pig''s intestinal epithelium.