[Acute effects of peritoneal dialysis on muscle protein turnover].
BACKGROUND
Despite continuing glucose absorption and stimulation of insulin secretion, wasting is common in patients with chronic renal failure (CRF) treated with peritoneal dialysis.


METHODS
To evaluate if peritoneal dialysis per se has any effect(s) on muscle protein turnover we employed the forearm perfusion method associated with the kinetics of 3H-phenylalanine in seventeen patients with CRF in the basal state and: a) during the systemic hyperinsulinemia associated with peritoneal dialysis (6 patients) (200-240 min); b) during locally-induced hyperinsulinemia, without systemic effects on aminoacid (AA) availability (6 patients) (80-120 min); c) in time-controls (5 patients) (80-240 min).


RESULTS
Peritoneal dialysis and local infusion of insulin in the brachial artery (0.01 mU/min/kg) induced a similar degree of systemic or local, moderate hyperinsulinemia (19+/-4 e 21+/-3 microU/ml, respectively). During both protocols an insulin-related inhibition of muscle protein degradation occurred; however peritoneal dialysis caused a 20% decrease in forearm phenylalanine rate of disposal (an index of muscle protein synthesis), which correlated with the decline of arterial BCAA and potassium, which were removed via the peritoneal fluid. Furthermore, a persistent negative net phenylalanine and AA balance across the forearm was observed during peritoneal dialysis, while the negative basal net phenylalanine and AA balance was reversed to a positive or neutral one during local hyperinsulinemia.


CONCLUSIONS
We conclude that in CRF patients even a modest elevation in local insulin levels is followed by an anabolic muscle response, while the same effect is not observed during the systemic hyperinsulinemia associated with substrate removal which occurs during peritoneal dialysis. In this setting the antiproteolytic effect of hyperinsulinemia is offset by a decrease in muscle protein synthesis which is accounted for by a decrease in AA availability. Our data indicate that protein metabolism during peritoneal dialysis is characterized not only by decreased, but also less efficient, turnover rates.
Sofia
A
A
Divisione di Nefrologia, Dipartimento di Medicina Interna, Universita' di Genova, Genova.
Russo
R
R
Saffioti
S
S
Sacco
P
P
Dertenois
L
L
Pastorino
N
N
Verzola
D
D
Ravera
F
F
Deferrari
G
G
Garibotto
G
G
D000596:Amino Acids / Q000378:metabolism; D001916:Brachial Artery; D015314:Dialysis Solutions / Q000009:adverse effects; D005542:Forearm; D005947:Glucose / Q000008:administration & dosage / Q000009:adverse effects; D006801:Humans; D006946:Hyperinsulinism / Q000139:chemically induced / Q000378:metabolism; D007261:Infusions, Intra-Arterial; D007328:Insulin / Q000008:administration & dosage / Q000494:pharmacology; D007676:Kidney Failure, Chronic / Q000378:metabolism / Q000628:therapy; D009124:Muscle Proteins / Q000378:metabolism; D010530:Peritoneal Dialysis; D010649:Phenylalanine / Q000493:pharmacokinetics; D011502:Protein-Energy Malnutrition / Q000150:complications / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D014316:Tritium / Q000032:analysis
D000596:Amino Acids; D015314:Dialysis Solutions; D007328:Insulin; D009124:Muscle Proteins; D011506:Proteins; D014316:Tritium; D010649:Phenylalanine; D005947:Glucose