Protein synthesis and growth in uremic rats with and without chronic metabolic acidosis.

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).