Distributional Uptake of γ-Globulin in Small Intestine of Neonatal Calves

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Abstract
Newborn calves deprived of colostrum were used to determine distribution of uptake of .gamma.-globulin labeled with iodine-125 in the small intestine. Ten calves < 12.5 h of age (average 7 h) were anesthetized and intestines were exteriorized through an abdominal incision. Intestine was ligated into 10 cm segments, 70 cm apart, beginning at the ileocecal junction and progressing anteriorally; each segment was injected with 100 mg (.apprxeq. 1 .mu.Ci) labeled .gamma.-globulin in 5 ml electrolyte solution and incuvated for 1.5 h. One additional segment was formed adjacent to segments 1, 5 and 10 to assess uptake after 0.5 h incubation with [iodine-125] .gamma.-globulin. After prescribed .gamma.-globulin exposure segments were excised; the volume of lumen contents, segment weight and tissue activity were measured. The location of each segment was the percentage of distance from cecum to abomasum. Uptake was measured as mg .gamma.-globulin/g of segment tissue. Distribution of .gamma.-globulin uptake after 1.5 h incubation was a cubic function of segment position. Uptake was greatest in a region 15% of the cecum-abomasum distance and declined progressively toward the abomasum. After 0.5 h incubation with .gamma.-globulin, regression of uptake on segment position was a quadratic function with greatest uptake at 30% cecum-abomasum distance. Uptake was greater in segments exposed to .gamma.-globulin for 1.5 than 0.5 h.