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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.

Renal clearance of endogenous 5-HIAA has been shown to be similar to that of PAH in humans. The present study compared 5-HIAA and PAH clearances in rats. It showed that the clearance of 5-HIAA in rats was identical to that of inulin and creatinine. This suggests that in this species, 5-HIAA is only filtered and not secreted by the tubules in contrast to what is observed in humans.

The effects of uremia-induced chronic acidosis on fractional protein synthesis rate (FSR), degradation (FDR) and protein tissue growth (FRG) in skeletal muscle were examined in young rats fed a 30% protein diet. This diet induced acidosis in UA rats, which was corrected by NaHCO3 supplementation in UB rats. Blood pH and plasma HCO3- were 7.22 +/- 0.01 and 15.2 +/- 0.8 mmol/l in UA rats vs. 7.41 +/- 0.01 and 25.8 +/- 0.9 in UB rats. Both UA and UB groups had similar renal function and food intake. Acidosis impaired weight gain (4.0 +/- 0.3 vs. 5.0 +/- 0.4 g/day, p < 0.05) and length gain (0.31 +/- 0.02 vs. 0.42 +/- 0.02 cm/day, p < 0.001). UA and UB rats showed similar muscle FSR (10.4 +/- 0.5 vs. 10.8 +/- 0.5%/day) and RNA content (6.3 +/- 0.2 vs. 6.2 +/- 0.2 micrograms/g protein). UA rats had lower FGR than UB rats (3.9 +/- 0.8 vs. 5.9 +/- 0.6%/day, p < 0.05). Therefore, muscle FDR was increased in UA rats (6.30 +/- 0.99 vs. 5.10 +/- 0.7%/day).

To determine what levels of chronic metabolic acidosis affect growth in uremia, we compared two groups of uremic rats receiving a 30% protein diet. This diet induced acidosis in A rats (n = 52; pH: 6.9-7.35) which was prevented by the addition of NaHCO3 in the diet of B rats (n = 52; pH: 7.38-7.46). A rats were separated into five groups by increasing severity of acidosis and were matched with B rats of similar renal function. Comparison between A and B rats showed: (1) no difference in food intake; (2) a reduction of weight gain only for severe acidosis with pH around 7.20 or less; (3) a reduction of length gain which was observed for less severe acidosis than reduction of weight gain, but which did not exist for marginal acidosis (pH > 7.25).

Most of the paediatric patients presenting with nephrotic syndrome (NS) have a nephrosis (minimal glomerular changes with or without focal lesion NS) and most of them are characterized by a clear-cut steroid response: a complete remission is rapidly obtained with high dose of glucocorticoids. Many of them, however, relapse during or after the treatment's withdrawal. Most often, these patients can be managed for several years with long-term alternate-day steroid therapy. Alkylating agents must be used exclusively when the doses of steroids required result in severe toxicity. In other types of NS (steroid resistant nephrosis, membranous and membranoproliferative glomerulonephritides) the efficiency of drugs is not established. Whatever the cause for the NS, adequate supportive therapy is necessary. The constant aim is to allow the patient a normal physical, school and social activity.