[Breakdown of dietary proteins in the gastrointestinal tract of the adult rat].

Adult rats were examined for the time course of inactivation of antigenic determinants of tritium-labeled bovine serum albumin (BSA) or chicken ovalbumin administered intragastrically. Immunoreactive protein in the perfusates was determined according to the amount of the radioactive label retained by the immunosorbent. Antigenic determinants of protein disintegrated very rapidly after protein penetrated the gastrointestinal tract. Within 20 minutes after administration their amount did not exceed 12% of the dose administered. BSA disintegrated more rapidly than ovalbumin. At the same time after 20, 60 and 180 min an insignificant amount (about 1%) of immunoreactive protein penetrated the distal part of the small and large intestines. The amount of high-molecular fragments in all the parts of the gastrointestinal tract exceeded the discovered amount of immunoreactive protein. The data obtained indicate that a small amount of foreign food antigens is capable of overcoming the barrier of the cavitary proteolysis and of reaching those parts of the intestine where they can be absorbed in the intact form.