Feeding of alkali-textured protein to growing rats has induced cytomegalia in the proximal tubules of the kidney. This has been observed in one laboratory but not confirmed in another. When the presumed toxic factor of alkali-treated protein, lysinoalanine (LAL) was fed as the free amino acid, both laboratories observed nephrocytomegalia (NCM). The proposed research will investigate and quantify the contribution of important experimental factors to the availability of free LAL for NCM-induction in the rat. The factors include the roles of the gastrointestinal microflora, the cecum and coprophagy. Preliminary data on NCM in germfree rats indicate some of the microflora in increasing LAL availability. Control of the microflora by gnotobiotic techniques will permit quantitation of the microflora effect. Analyses of feces, urine and intestinal contents for free and protein-bound LAL in rats fed either free or protein-bound LAL will provide quantitation of microflora effects on LAL availability for correlation with the induction of NCM. Similar analyses in rats prevented from practicing coprophagy and in cecectomized rats will provide estimates of the contribution of cecal detention and coprophagy to LAL availability and NCM-induction in both germfree and coventional rats. Further confirmation of the microflora effects will be obtained by associating germfree rats with microfloras selected on the basis of their in vitro ability to free or destroy the LAL in alkali-treated protein. Estimates will be made of minimum doses of LAL required for NCM induction when the LAL is delivered directly to the renal artery of rats or other species. Tissue culture studies of rat, human and other types of tissues will investigate concentrations of LAL which might have effects at the cellular level. This investigation of factors which contribute to NCM-induction in the rat, especially of those factors in which the rat differs substantially from the human consumer of LAL-containing proteins, will aid in determining if the response of conventional rats has any applicability to that of the human consumer of alkali-textured proteins and other processed foods which contain LAL.