Nitrogen Deficits in Aroclor 1254-Treated Rats

Abstract

Nitrogen Deficits in Aroclor 1254-Treated Rats. EBNER, K. V., BERGEN, W. G., and BRASELTON, W. E., Jr. (1987). Fundam. Appl. Toxicol. 8, 89–96. Nitrogen balance and the efficiency of retaining assimilated dietary nitrogen (biological value) were evaluated in Aroclor 1254-treated (ARO) rats and in vehicle-treated, pair-fed (PF) and ad libitum-fed (AF) rats (150–190 g). ARO-treated rats (300 mg/kg/day, po on 4 consecutive days) lost weight and consumed less chow than the AF group while the weight of the PF rats was not different from those of either the ARO or AF groups. The nitrogen balance and the biological value for the ARO rats were also significantly less than those of the AF rats whereas the PF controls were not different. The ingested calories (expressed in kcal/(kg body wt)0.73) by the ARO and PF rats were equal, but were less than those of the AF group. The ARO and PF groups excreted the same amounts of fecal nitrogen which were less than the fecal nitrogen excretion by the AF rats. The absorbed fraction of the ingested nitrogen was the same among all groups, which indicated that the digestibility and absorption of the dietary nitrogen were not changed. By contrast, the ARO group excreted the same amount of urinary nitrogen and urea as AF rats while the PF group excreted significantly less urinary nitrogen than the latter controls. Thus, the loss of nitrogen by the ARO group was attributed to increased excretion of urinary nitrogen, most likely as urea, in relation to the nitrogen intake. The nitrogen retention and balance in rats with ARO exposure are similar to the response in rats fed a diet of low biological value except that the influence of ARO on nitrogen metabolism occurred during the postabsorption phase.