Rate of synthetic oligosaccharide degradation as a novel measure of amylase activity in peritoneal dialysis patients.
BACKGROUND
Plasma alpha-amylase activity is elevated in uremic patients but lower in peritoneal dialysis (PD) patients using icodextrin in comparison to healthy controls. We studied the rate by which an exogenous oligosaccharide (maltoheptaose; G7) is degraded ex vivo by amylase in plasma from PD patients treated with glucose or icodextrin PD solutions.


METHODS
Plasma amylase (pancreatic and total) activity and concentration were measured in 11 controls and in PD patients treated with glucose (n = 11) and icodextrin (n = 19). The plasma was spiked with G7 and/or synthetic amylase and the metabolites formed were measured by HPLC following incubation at 37 degrees C for 4 hours.


RESULTS
The relationship between amylase activity and amylase concentration was similar in all patients and controls. The G7 degradation rate was slower in plasma from icodextrin patients but it was also reduced in patients using glucose compared with the controls, in spite of the higher amylase activity in the glucose group. Normalization (by spiking) of patient plasma with porcine amylase increased but did not normalize the speed of G7 degradation. At a given endogenous amylase activity level, the efficiency of G7 degradation was similar for both patient groups.


CONCLUSIONS
An ex vivo model to study the relationship between amylase activity and the actual rate of carbohydrate (represented by G7) breakdown was developed and showed that PD patients using glucose and icodextrin degrade G7 at a slower speed than controls. This suggests that amylase-mediated carbohydrate metabolism is reduced in PD patients. Further clinical studies are needed to confirm if these findings hold true also in other groups of uremic patients with varying degrees of kidney failure, as well as in patients undergoing hemodialysis.
García-López
Elvia
E
Divisions of Baxter Novum and Renal Medicine, Karolinska Institutet, Stockholm, Sweden.
Werynski
Andrzej
A
Heimbürger
Olof
O
Filho
José C Divino
JC
Lindholm
Bengt
B
Anderstam
Björn
B
D000368:Aged; D016022:Case-Control Studies; D015314:Dialysis Solutions / Q000378:metabolism / Q000627:therapeutic use*; D005260:Female; D005936:Glucans / Q000378:metabolism*; D005947:Glucose / Q000493:pharmacokinetics*; D006801:Humans; D000077607:Icodextrin; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis; D010537:Peritoneum / Q000378:metabolism; D015203:Reproducibility of Results; D013997:Time Factors; D000516:alpha-Amylases / Q000097:blood / Q000378:metabolism*
D015314:Dialysis Solutions; D005936:Glucans; D000077607:Icodextrin; C031146:maltoheptaose; D000516:alpha-Amylases; D005947:Glucose