In the preceding paper, the adverse influence of the indigenous microbial flora on rats rendered uremic by bilateral nephrectomy was shown by a comparison of the postnephrectomy survival times of germfree (GF), limited-flora, and conventionalized (CONV) rats (I). This report concerns the histopathology of these animals and the biochemical and morphologic observations on groups of G F and CONV rats sacrificed 48 and 72 hr after bilateral nephrectomy and of their controls. These studies have provided some correlations between the metabolic and structural alterations of the renoprival state. They reveal that uremic colitis is bacterially induced, that cardiovascular pathology is modified by the microbial state of the host, and provide tangible evidence of the effect of the indigenous microbial flora on the uremic host.
Materials and MethodsChemistry.--Chemical determinations were made on a group of rats separate from those previously reported (1). 4-to 6-month-old germfree Fischer rats were used. Half were conventionalized a month before surgery as previously described (1). Bilateral nephrectomy or sham nephrectomy was performed as before (1) under halothane anesthesia (2). 48 or 72 hr after surgery, rats were removed from their isolators and anesthetized with halothane. 10 mg/kg body weight of sodium heparin (u.s.P., without preservative) in sterile isotonic saline were given intraperitoneally. Laparotomy was performed, the abdominal aorta was cannniated with PE 50 tubing, and the rats were exsanguinated; the variable volumes of blood collected *