Continuous enteral feeding in uremic rats

Because of constant uremia-induced anorexia, food restriction of normal rats is generally used to study the consequences of uremia. The effects of a normal food supply in uremic rats has never been tested, since no author has succeeded in providing normal intakes. Uremic rats either fed ad lib (U rats, n = 12) or force-fed through a gastric catheter (UF rats, n = 10), and sham-operated rats (C rats, n = 10) were compared from days 7 to 21 after surgery. U rats had lower food intake (13.8 vs. 17 g/day), weight gain (5.16 vs. 6.23 g/day), length gain (4 vs. 5 mm/day), nitrogen balance (228 vs. 279 mg/day) and muscle fractional protein synthesis rate (9.5 vs. 10.6%) measured in vivo by 3H-phenylalanine injection (p < 0.05 for all). All parameters were restored to normal values in UF rats, possibly due to correction of underhydration in addition to undernutrition. Such continuous enteral feeding may provide a model for normal nutritional supply in uremia.