Alterations of Polymorphonuclear Leukocyte Glycogen Metabolism and Glucose Uptake in Dialysis Patients Marianne Haag-Weber, MD, Michael Hable, MD, Gerd Fiedler, MD, Isabell Blum, PhD, Peter Schollmeyer, MD, Wilhelm Kreu~er, MD, and Walter H. Herl, MD, PhD • Human polymorphonuclear leukocytes (PMNs) are activated during extracorporeal circulation. An indicator of PMN activation may be the glycogen-degrading enzyme phosphorylase. h is unknown whether dialysis therapy may Influence PMN carbohydrate metabolism. Therefore, PMNs were Isolated from healthy control subjects, patients undergoing continuous ambulatory peritoneal dialysis (CAPD), and patients undergoing regular hemodialysis therapy (RDT) before, during, and at the end of hemodialysis (HD) treatment using dialyzers made of polysulfone or polymethylmethacrylate (PMMA). Nifedlplne (NIF) was continuously infused during HD with PMMA in 5 patients at a dose of 18 Jlg/kg body weight per hour. Glycogen, activity of glycogen synthetase and phosphorylase (active and inactive forms of both enzymes), and glucose uptake with and without stimulation with the chemotactic peptide FMLP were determined In these PMNs. During HD with PMMA, there was a significant Increase of PMN phosphorylase "a" activity 15 and 30 minutes after the start of HD. HD with polysulfone did not stimulate the active "a" form of the glycogen-degrading enzyme In PMNs. HD with PMMA significantly inhibited the active 1form of glycogen synthetase, whereas polysulfone activated glycogen synthetase I. NIF Inhibited phosphorylase "a" activation during HD with PMMA. PMN glycogen content and glucose uptake were improved during HD with polysulfone, but not with PMMA. PMN glycogen content, activity of glycogen synthetase, and glucose uptake were significantly lower also in CAPD patients compared with healthy controls. These data show that HD with PMMA activates PMN glycogenolysis. This effect can be inhibited by calcium channel blockers. PMN glycogen content of RDT and CAPD patients is significantly lower compared with healthy controls due to inhibition of glycogen synthesis. Elimination of dialyzable factor(s) improves, but does not restore, PMN glycogen synthesis and glucose uptake. © 1991 by the National Kidney Foundation, Inc. INDEX WORDS: Polymorphonuclear neutrophilsj glucosej dialyslsj glycogen metabolism.
N
EUTROPHIL activation during hemodialysis includes binding of C5a and C5a des Arg to specific polymorphonuclear leukocyte (PMN) receptors inducing aggregation of these cells,1.2 the adherence of the PMNs to endothelial cells,3 the release of active oxygen radicals,4 degranulation, S stimulation of arachidonate metabolism ,6.7 and enhanced phagocytotic capacity. 8 Phagocytosis in uremic patients has been reported to be normal or slightly diminished. 9 - 12 Hirabayashi et al l3 found decreased phagocytotic uptake of IgG-coated particles in hemodialysis (HD) patients before dialysis, which was restored after treatment. Impaired phagocytosis in chronically uremic patients is related to significantly
From the Department of Medicine. Division of Nephrology. University of Freiburg. Germany. and Marien-Hospital. Duisburg. Germany Supported by the Deutsche Forschungsgemeinschaft (Ho 78114-1). Address reprint requests to Walter H. Horl. MD. PhD. Professor of Medicine and Nephrology. Medizinische Universitatsklinik. Hugstetterstrasse 55. D-7800 Freiburg i. Br. . Germany. © 1991 by the National Kidney Foundation. Inc. 0272-6386/91/1705-0009$3.00/0 562
lower glucose uptake, oxygen consumption, and lactate production by PMNs.14 It is unknown whether dialysis therapy may influence PMN carbohydrate metabolism. Therefore, PMN glycogen metabolism and glucose uptake were investigated in patients undergoing regular hemodialysis (RDT) and continuous ambulatory peritoneal dialysis (CAPD) with particular reference to dialyzer membrane material and pharmacological interventions. METHODS
Patients and Blood Samples We studied 14 healthy control subjects (CO) with a mean age of 42.3 ± 3.4 years, and nine patients undergoing regular hemodialysis treatment (RDT patients) with dialyzers made of polysulfone (Fresenius, Oberursel, Germany) (mean age, 59.3 ± 2. 1 years; duration of HD, 38.3 ± 12.0 months) and with polymethylmethacrylate (PMMA) dialyzers (Toray, Tokio, Japan) (mean age, 58.3 ± 2 .6 years; duration of HD, 35.6 ± 11.8 months) . A comparison of their clinical data and laboratory findings is presented in Table I. All RDT patients underwent maintenance dialysis for 3 to 4 hours, three times per week. In an additional experiment, five of the RDT patients dialyzed with PMMA were continuously infused with the calcium channel blocker nifedipine (NIF) in a dose of 18 Jlg/kg/h during one HD. In addition, we investigated eight chronically
American Journal of Kidney Diseases. Vol XVII, No 5 (May), 1991 : pp 562-568
563
PMN GLYCOGEN METABOLISM AND GLUCOSE UPTAKE
Table 1.
Laboratory Findings of Healthy Controls, ROT Patients Dialyzed with Polysulfone and PMMA, and CAPO Patients Creatinine /Lmol/L
Controls (n = 14) RDT (n = 9) with polysulfone RDT (n = 9) with PMMA CAPD (n = 8)
Urea mg/dL
mmol/L
mg/dL
WBC Count (1,OOOI/LL)
88.4 ± 4.42
1.0 ± 0.05
12.7 ± 1.0
35.7 ± 2.7
7.4 ± 0.34
778.0 ± 53.0
8.8 ± 0.60
57.1 ± 3.2
159.9 ± 9.0
7.9 ± 0.35
742.6 ± 62.0 1,025.4 ± 106.1
8.4 ± 0.70 11.6 ± 1.20
55.1 ± 3.1 53.3 ± 4.4
154.3 ± 8.7 149.2 ± 12.3
7.0 ± 0.54 7.4 ± 0.70
NOTE. Values are mean ± SEM.
uremic patients on CAPD (mean age, 57.5 ± 4.3 years; duration of CAPD, 11.6 ± 1.2 months). CAPD patients were daily treated with three bags (2 L each) containing 1.36% of glucose and one bag (2 L) containing 3.86% of glucose. None of the patients studied had clinical evidence for infection at the time of study. Informed consent according to the declaration of Helsinki was obtained from all patients. Blood samples were obtained from CO and CAPD patients in the morning, and from RDT patients before HD, 15, 30, 60 minutes after begin of HD, and at the end of HD. In RDT patients, blood was taken from the arteriovenous fistula.
Preparation of PMNs PMNs were prepared from 10 mL whole blood anticoagulated with 1.5% Na-EDTA in phosphate-buffered saline (PBS) as described by Harbeck et al.l5 In 15-mL conical tubes, 5 mL of 63 % percoll was placed. This was underJayered with 5 mL of 72 % percoll. Five milliliters of undiluted EDTA-blood was layered on this gradient. This was centrifuged at 500 x g for 25 minutes at room temperature. PMNs were harvested in the 2 supernatant and were washed two times with PBS without Ca + and The cells were then resuspended in the media needed for the assay. Viability of PMNs was tested by trypan blue. Viability was always greater than 90%.
Ml+.
Metabolic Assays Glycogen synthetase was assayed in PMNs according to Thomas et al. 16 Isolated PMNs were resuspended in ci+ and -free PBS and adjusted to a concentration of 1 x 107 cells/mL. The cells were ultrasonically disintegrated for 5 seconds. Fifty microliters of the homogenate were assayed on ice with 50 /LL of a mixture that contained 5 mCi/L(,H)-uridine diphosphate (UDP) glucose, 33 mmollL Tris-HCl, 3.3 mmollL EDTA, 6.6 giL glycogen, 4.5 mmollL UDP-glucose, and with or without glucose-6-phosphate. This mixture (with glucose-6phosphate in a final concentration of 4.5 mmollL) was incubated for 20 minutes for total glycogen synthetase activity (D+ I-forms) and (without glucose-6-phosphate) for 60 minutes for the active form of glycogen synthetase (independent I-form) at 37°C. After incubation, 75 ILL of this mixture was placed on Whatman filter paper (2 x 2 cm, Whatman 31 ET, Maidstone, England). The filter papers were washed with 66% ethanol, followed by a final acetone rinse. The amount of radioactivity was determined in a liquid scintillation counter (Tri-Carb 2000 CA, Packard, Frankfurt, Germany).
Ml+
~7cogen phosphorylase was analyzed in the PMNs (50 ILL; 10 cells/mL) according to Slonczewski et al.'7 The assay procedure was the same as for determination of glycogen synthetase with one exception; the solution (50 ILL) in which the incorporation of radioactive glucose-I-phosphate into glycogen with glycogen phosphorylase takes place contained the following: 10 mmol/L glucose-I-phosphate, 10 giL glycogen, 100 mmollL sodium fluoride, 66.5 mmol/L PIPES (Sigma, Munich, Germany), 0.5 mCi/L 14C-glucose-l-phosphate. Total enzyme activity was determined in the presence of adenosine monophosphate (AMP; 1 mmollL) in the solution and the active "a" form of phosphorylase in the absence of AMP. Glycogen was determined in PMNs using the filter paper technique according to SoIling and Esmann. 18 A PMN suspension of cells (l x 107 ) was ultrasonically disintegrated as described above. One hundred microliters of the homogenate were pipetted onto 2 x 2 cm of Whatman filter paper. The paper was washed with ice-cold 66% ethanol with a final rinse of acetone. The dried filter paper was placed in a 15-mL tube that contained a thoroughly mixed preparation of 300 ILL of 0.1 mollL acetate buffer, pH 4.75, and 30 ILL of aminoglycosidase (4.5 U). The mixture was then left standing for 10 minutes at room temperature for the degradation of glycogen. The released glucose was determined with a commercially available assay (Merckotest Glucose, Merck, Darmstadt, Germany). Hexose uptake was determined by the method described by McCall et al,l9 PMNs were resuspended in PBS (with Ca2+ 2 and Mg +) at a concentration of 1 x 106 cells/mL. Triplicate assays were performed in 1.5-mL test tubes that contained 200 ILL of cell suspension and 10 ILL PBS or 10 ILL of the stimulating factor formyl-methionyl-leucyl-phenylalanine (FMLP) (Sigma) (l x 10- 6 mmollL). PMNs were preincubated for 15 minutes at 37°C in a shaking water bath. Uptake was initiated by the addition of 0.5 /LCi (,H)D-glucose (10 nmollL; uptake was terminated after 60 minutes by the addition of 1 mL iced PBS: the samples were then centrifuged at 1,000 x g for 20 seconds. The pellet was washed with 1 mL of iced PBS and again centrifuged. The supernatant was removed by aspiration, and the pellet and tube were placed in a scintillation vial containing 10 mL of Aquasone (Packard). Radioactivity was determined with a liquid scintillation counter (Packard).
Statistical Methods Data are given as mean values ± SEM. For analysis of significance, the paired and unpaired Student's t test was used.
564
HAAG-WEBER ET AL
RESULTS
Figure 1 shows the active "a"-form of the glycogen-degrading enzyme phosphorylase. Figure lA displays data obtained with patients on dialyzers made of PMMA, while Fig IB shows the results obtained with dialyzers made of polysulfone. PMN phosphorylase "a" activity increases significantly during HD with PMMA dialyzers, but not with dialyzers made of polysulfone. Predialysis phosphorylase "a" activity in the PMN of HD patients was comparable to that in control subjects (0.42 ± 0.04 v 0.41 ± 0.06 mU/ 106 PMN). There is also a significant increase in total enzyme activity during HD therapy with PMMA membranes (before HD, 1.53 ± 0.13; 15 minutes, 2.10 ± 0.40, P < 0.05; 30 minutes, 1.76 ± 0.10 mU/10 6 PMN, P < 0.05). Again, total phosphorylase activity remained unchanged during dialysis with poly sulfone membranes (before HD, 1.46 ± 0.18; 15 minutes, 1.44 ± 0.15 ; 30 minutes, 1.37 ± 0.17 mUIl06 PMN).
)lUI106 PMNs
CO
Polysulfone
250
* * 200 PMMA
150
*
100
n*
~
50
o
+ *
180
o
180
min
PMMA
*
mU/l06 PMNs
0.5
i+-
+t
Fig 2. Glycogen synthetase I activity in PMNs of healthy controls (CO) and of ROT patients before (0) and at the end of HO (180 min) using dialyzers made of PMMA and polysulfone. 'P < 0.05 healthy controls versus ROT patients; "P < 0.05 before HO versus end of HO.
*
r+
0 ,25
o
15
30
80
180
min
180
min
PolYlulfone
0,5
0 ;25
o
15
30
60
Fig 1. Phosphorylase "a" activity in PMNs of ROT patients before HO, and 15, 30, 60, and 180 minutes after start of HO. Phosphorylase "a" activity during HO with PMMA (top); activity using membrane made of polysulfone (bottom) .• P < 0.05 before HO versus during HO.
Figure 2 depicts the active I-form of glycogen synthetase in PMNs of healthy subjects and RDT patients before and at the end of dialysis therapy. Glycogen synthetase I activity was significantly lower in PMNs of RDT patients compared with healthy controls. The enzyme activity decreased significantly in patients dialyzed with PMMA dialyzers, but increased significantly in PMNs of patients dialyzed with dialyzers made of polysulfone. Figure 3 shows glycogen concentration and glucose uptake in PMNs of healthy controls and RDT patients before and after HD with polysulfone. PMN glycogen content was significantly lower in RDT patients compared with controls . HD treatment caused a significant increase in neutrophil glycogen content. However, the mean values remained significantly lower than in healthy subjects. Glucose uptake of PMNs of RDT patients was markedly lower compared with healthy controls. Again, HD therapy with polysulfone membranes caused increased glucose uptake. The mean values also remained significantly lower compared
565
PMN GLYCOGEN METABOLISM AND GLUCOSE UPTAKE
B
A
••
+ +
8.000
•
0;
z
...:I
••
~
'""
E Co
Fig 3. FMLP-stimulated glucose uptake (A) and glycogen content (8) of PMNs of healthy controls (CO) and ROT patients before HO (0) and at the end of HO (180 min) using dialyzers made of polysulfone • • p < 0.05 healthy controls versus ROT patients; •• p < 0.05 before HO versus end of HO.
.:;
4.000
•
"""co
15.
=.,c '",.. 0
"
o
.a" Cl
N
EUTROPHIL activation during hemodialysis includes binding of C5a and C5a des Arg to specific polymorphonuclear leukocyte (PMN) receptors inducing aggregation of these cells,1.2 the adherence of the PMNs to endothelial cells,3 the release of active oxygen radicals,4 degranulation, S stimulation of arachidonate metabolism ,6.7 and enhanced phagocytotic capacity. 8 Phagocytosis in uremic patients has been reported to be normal or slightly diminished. 9 - 12 Hirabayashi et al l3 found decreased phagocytotic uptake of IgG-coated particles in hemodialysis (HD) patients before dialysis, which was restored after treatment. Impaired phagocytosis in chronically uremic patients is related to significantly
From the Department of Medicine. Division of Nephrology. University of Freiburg. Germany. and Marien-Hospital. Duisburg. Germany Supported by the Deutsche Forschungsgemeinschaft (Ho 78114-1). Address reprint requests to Walter H. Horl. MD. PhD. Professor of Medicine and Nephrology. Medizinische Universitatsklinik. Hugstetterstrasse 55. D-7800 Freiburg i. Br. . Germany. © 1991 by the National Kidney Foundation. Inc. 0272-6386/91/1705-0009$3.00/0 562
lower glucose uptake, oxygen consumption, and lactate production by PMNs.14 It is unknown whether dialysis therapy may influence PMN carbohydrate metabolism. Therefore, PMN glycogen metabolism and glucose uptake were investigated in patients undergoing regular hemodialysis (RDT) and continuous ambulatory peritoneal dialysis (CAPD) with particular reference to dialyzer membrane material and pharmacological interventions. METHODS
Patients and Blood Samples We studied 14 healthy control subjects (CO) with a mean age of 42.3 ± 3.4 years, and nine patients undergoing regular hemodialysis treatment (RDT patients) with dialyzers made of polysulfone (Fresenius, Oberursel, Germany) (mean age, 59.3 ± 2. 1 years; duration of HD, 38.3 ± 12.0 months) and with polymethylmethacrylate (PMMA) dialyzers (Toray, Tokio, Japan) (mean age, 58.3 ± 2 .6 years; duration of HD, 35.6 ± 11.8 months) . A comparison of their clinical data and laboratory findings is presented in Table I. All RDT patients underwent maintenance dialysis for 3 to 4 hours, three times per week. In an additional experiment, five of the RDT patients dialyzed with PMMA were continuously infused with the calcium channel blocker nifedipine (NIF) in a dose of 18 Jlg/kg/h during one HD. In addition, we investigated eight chronically
American Journal of Kidney Diseases. Vol XVII, No 5 (May), 1991 : pp 562-568
563
PMN GLYCOGEN METABOLISM AND GLUCOSE UPTAKE
Table 1.
Laboratory Findings of Healthy Controls, ROT Patients Dialyzed with Polysulfone and PMMA, and CAPO Patients Creatinine /Lmol/L
Controls (n = 14) RDT (n = 9) with polysulfone RDT (n = 9) with PMMA CAPD (n = 8)
Urea mg/dL
mmol/L
mg/dL
WBC Count (1,OOOI/LL)
88.4 ± 4.42
1.0 ± 0.05
12.7 ± 1.0
35.7 ± 2.7
7.4 ± 0.34
778.0 ± 53.0
8.8 ± 0.60
57.1 ± 3.2
159.9 ± 9.0
7.9 ± 0.35
742.6 ± 62.0 1,025.4 ± 106.1
8.4 ± 0.70 11.6 ± 1.20
55.1 ± 3.1 53.3 ± 4.4
154.3 ± 8.7 149.2 ± 12.3
7.0 ± 0.54 7.4 ± 0.70
NOTE. Values are mean ± SEM.
uremic patients on CAPD (mean age, 57.5 ± 4.3 years; duration of CAPD, 11.6 ± 1.2 months). CAPD patients were daily treated with three bags (2 L each) containing 1.36% of glucose and one bag (2 L) containing 3.86% of glucose. None of the patients studied had clinical evidence for infection at the time of study. Informed consent according to the declaration of Helsinki was obtained from all patients. Blood samples were obtained from CO and CAPD patients in the morning, and from RDT patients before HD, 15, 30, 60 minutes after begin of HD, and at the end of HD. In RDT patients, blood was taken from the arteriovenous fistula.
Preparation of PMNs PMNs were prepared from 10 mL whole blood anticoagulated with 1.5% Na-EDTA in phosphate-buffered saline (PBS) as described by Harbeck et al.l5 In 15-mL conical tubes, 5 mL of 63 % percoll was placed. This was underJayered with 5 mL of 72 % percoll. Five milliliters of undiluted EDTA-blood was layered on this gradient. This was centrifuged at 500 x g for 25 minutes at room temperature. PMNs were harvested in the 2 supernatant and were washed two times with PBS without Ca + and The cells were then resuspended in the media needed for the assay. Viability of PMNs was tested by trypan blue. Viability was always greater than 90%.
Ml+.
Metabolic Assays Glycogen synthetase was assayed in PMNs according to Thomas et al. 16 Isolated PMNs were resuspended in ci+ and -free PBS and adjusted to a concentration of 1 x 107 cells/mL. The cells were ultrasonically disintegrated for 5 seconds. Fifty microliters of the homogenate were assayed on ice with 50 /LL of a mixture that contained 5 mCi/L(,H)-uridine diphosphate (UDP) glucose, 33 mmollL Tris-HCl, 3.3 mmollL EDTA, 6.6 giL glycogen, 4.5 mmollL UDP-glucose, and with or without glucose-6-phosphate. This mixture (with glucose-6phosphate in a final concentration of 4.5 mmollL) was incubated for 20 minutes for total glycogen synthetase activity (D+ I-forms) and (without glucose-6-phosphate) for 60 minutes for the active form of glycogen synthetase (independent I-form) at 37°C. After incubation, 75 ILL of this mixture was placed on Whatman filter paper (2 x 2 cm, Whatman 31 ET, Maidstone, England). The filter papers were washed with 66% ethanol, followed by a final acetone rinse. The amount of radioactivity was determined in a liquid scintillation counter (Tri-Carb 2000 CA, Packard, Frankfurt, Germany).
Ml+
~7cogen phosphorylase was analyzed in the PMNs (50 ILL; 10 cells/mL) according to Slonczewski et al.'7 The assay procedure was the same as for determination of glycogen synthetase with one exception; the solution (50 ILL) in which the incorporation of radioactive glucose-I-phosphate into glycogen with glycogen phosphorylase takes place contained the following: 10 mmol/L glucose-I-phosphate, 10 giL glycogen, 100 mmollL sodium fluoride, 66.5 mmol/L PIPES (Sigma, Munich, Germany), 0.5 mCi/L 14C-glucose-l-phosphate. Total enzyme activity was determined in the presence of adenosine monophosphate (AMP; 1 mmollL) in the solution and the active "a" form of phosphorylase in the absence of AMP. Glycogen was determined in PMNs using the filter paper technique according to SoIling and Esmann. 18 A PMN suspension of cells (l x 107 ) was ultrasonically disintegrated as described above. One hundred microliters of the homogenate were pipetted onto 2 x 2 cm of Whatman filter paper. The paper was washed with ice-cold 66% ethanol with a final rinse of acetone. The dried filter paper was placed in a 15-mL tube that contained a thoroughly mixed preparation of 300 ILL of 0.1 mollL acetate buffer, pH 4.75, and 30 ILL of aminoglycosidase (4.5 U). The mixture was then left standing for 10 minutes at room temperature for the degradation of glycogen. The released glucose was determined with a commercially available assay (Merckotest Glucose, Merck, Darmstadt, Germany). Hexose uptake was determined by the method described by McCall et al,l9 PMNs were resuspended in PBS (with Ca2+ 2 and Mg +) at a concentration of 1 x 106 cells/mL. Triplicate assays were performed in 1.5-mL test tubes that contained 200 ILL of cell suspension and 10 ILL PBS or 10 ILL of the stimulating factor formyl-methionyl-leucyl-phenylalanine (FMLP) (Sigma) (l x 10- 6 mmollL). PMNs were preincubated for 15 minutes at 37°C in a shaking water bath. Uptake was initiated by the addition of 0.5 /LCi (,H)D-glucose (10 nmollL; uptake was terminated after 60 minutes by the addition of 1 mL iced PBS: the samples were then centrifuged at 1,000 x g for 20 seconds. The pellet was washed with 1 mL of iced PBS and again centrifuged. The supernatant was removed by aspiration, and the pellet and tube were placed in a scintillation vial containing 10 mL of Aquasone (Packard). Radioactivity was determined with a liquid scintillation counter (Packard).
Statistical Methods Data are given as mean values ± SEM. For analysis of significance, the paired and unpaired Student's t test was used.
564
HAAG-WEBER ET AL
RESULTS
Figure 1 shows the active "a"-form of the glycogen-degrading enzyme phosphorylase. Figure lA displays data obtained with patients on dialyzers made of PMMA, while Fig IB shows the results obtained with dialyzers made of polysulfone. PMN phosphorylase "a" activity increases significantly during HD with PMMA dialyzers, but not with dialyzers made of polysulfone. Predialysis phosphorylase "a" activity in the PMN of HD patients was comparable to that in control subjects (0.42 ± 0.04 v 0.41 ± 0.06 mU/ 106 PMN). There is also a significant increase in total enzyme activity during HD therapy with PMMA membranes (before HD, 1.53 ± 0.13; 15 minutes, 2.10 ± 0.40, P < 0.05; 30 minutes, 1.76 ± 0.10 mU/10 6 PMN, P < 0.05). Again, total phosphorylase activity remained unchanged during dialysis with poly sulfone membranes (before HD, 1.46 ± 0.18; 15 minutes, 1.44 ± 0.15 ; 30 minutes, 1.37 ± 0.17 mUIl06 PMN).
)lUI106 PMNs
CO
Polysulfone
250
* * 200 PMMA
150
*
100
n*
~
50
o
+ *
180
o
180
min
PMMA
*
mU/l06 PMNs
0.5
i+-
+t
Fig 2. Glycogen synthetase I activity in PMNs of healthy controls (CO) and of ROT patients before (0) and at the end of HO (180 min) using dialyzers made of PMMA and polysulfone. 'P < 0.05 healthy controls versus ROT patients; "P < 0.05 before HO versus end of HO.
*
r+
0 ,25
o
15
30
80
180
min
180
min
PolYlulfone
0,5
0 ;25
o
15
30
60
Fig 1. Phosphorylase "a" activity in PMNs of ROT patients before HO, and 15, 30, 60, and 180 minutes after start of HO. Phosphorylase "a" activity during HO with PMMA (top); activity using membrane made of polysulfone (bottom) .• P < 0.05 before HO versus during HO.
Figure 2 depicts the active I-form of glycogen synthetase in PMNs of healthy subjects and RDT patients before and at the end of dialysis therapy. Glycogen synthetase I activity was significantly lower in PMNs of RDT patients compared with healthy controls. The enzyme activity decreased significantly in patients dialyzed with PMMA dialyzers, but increased significantly in PMNs of patients dialyzed with dialyzers made of polysulfone. Figure 3 shows glycogen concentration and glucose uptake in PMNs of healthy controls and RDT patients before and after HD with polysulfone. PMN glycogen content was significantly lower in RDT patients compared with controls . HD treatment caused a significant increase in neutrophil glycogen content. However, the mean values remained significantly lower than in healthy subjects. Glucose uptake of PMNs of RDT patients was markedly lower compared with healthy controls. Again, HD therapy with polysulfone membranes caused increased glucose uptake. The mean values also remained significantly lower compared
565
PMN GLYCOGEN METABOLISM AND GLUCOSE UPTAKE
B
A
••
+ +
8.000
•
0;
z
...:I
••
~
'""
E Co
Fig 3. FMLP-stimulated glucose uptake (A) and glycogen content (8) of PMNs of healthy controls (CO) and ROT patients before HO (0) and at the end of HO (180 min) using dialyzers made of polysulfone • • p < 0.05 healthy controls versus ROT patients; •• p < 0.05 before HO versus end of HO.
.:;
4.000
•
"""co
15.
=.,c '",.. 0
"
o
.a" Cl
