GAMMA GLOBULIN TURNOVER AND INTESTINAL DEGRADATION OF GAMMA GLOBULIN IN THE DOG*

Abstract

The turnover of I131-labeled canine gamma globulin was studied in 10 dogs. Four to 7 weeks later a second dose of I131 -labeled gamma globulin was injected intravenously into the same dogs, and the transfer of protein-bound radioactivity from plasma to isolated intestinal segments was measured. The turnover rate of gamma globulin was an average of 21% of the plasma pool/day, corresponding to 97 mg/kg/day. The intestinal degradation of gamma globulin, as indicated by the transfer from plasma to the intestinal lumen, was an average of 38% of the total amount catabolized/day. A significant correlation (p< 0.02) was found between the exchange rate of gamma globulin with extravascular sites and the fraction of total turnover broken down intestinally. This suggests that the amount of gamma globulin catabolized intestinally is determined by the ability of gamma globulin to pass the capillary wall.