Acute effects of peritoneal dialysis with dialysates containing dextrose or dextrose and amino acids on muscle protein turnover in patients with chronic renal failure

Whether changes in substrate and insulin levels that occur during peritonea l dialysis (PD) have effects on muscle protein dynamics was evaluated by st udying muscle protein synthesis (PS), breakdown (PB), and net protein balan ce (NB) by the forearm perfusion method associated with the kinetics of 3H- phenylalanine in acute, crossover studies in which PD patients served as th eir own controls. Studies were performed (I) in the basal state and during PD with dialysates that contained dextrose alone in different concentration s (protocol 1: eight patients), (2) during PD with dialysates that containe d dextrose alone or dextrose and amino acids (AA) (protocol 2: five patient s), and (3) in time controls (five patients). PD with dextrose alone induce d (2) a two- to threefold increase in insulin, as well as a 20 to 25% decre ase in AA, mainly BCAA, levels; (2) an insulin-related decline (-18%) in fo rearm PB (P < 0.002); (3) a 20% decrease in muscle PS (P < 0.04), which was related to arterial BCAA and K+ (P < 0.02 to 0.05); (4) a persistent negat ive NE; and (5) a decrease in the efficiency of muscle protein turnover, ex pressed as the ratio NB/PB. PD with dextrose +AA versus PD with dextrose in duced (I) similarly high insulin levels but with a significant increase in total arterial AA (+30 to 110%), mainly valine; (2) a reduced release of AA from muscle (P < 0.05); and (3) a decrease in the negative NE observed dur ing PD with dextrose, owing to an increase (approximately 20%) in muscle PS , without any further effect on muscle PB. This study indicates that in PD patients in the fasting state, the moderate hyperinsulinemia that occurs du ring PD with dextrose alone causes an antiproteolytic action that is obscur ed by a parallel decrease in AA availability for PS. Conversely, the combin ed use of dextrose and AA results in a cumulative effect, because of the su ppression of endogenous muscle PB (induced by insulin) and the stimulation of muscle PS (induced by AA availability). The hypothesis, therefore, is th at in patients who are treated with PD, when fasting or when nutrient intak e is reduced, muscle mass could be maintained better by the combined use of dextrose and AA.