The Role Of Potassium And And Voltage-gated Potassium Channel 1.3 In Macrophage

Continuous Ambulatory Peritoneal Dialysis (CAPD) is one of the renal replacement therapies for end stage renal disease. However,peritoneal dialysis related peritonitis remains the major complication and factor causing technique failure in peritoneal dialysis patients ,meanwhile ,hypokalemia is another common complication ,the prevalence of hypokalemia is～10-36% in peritoneal dialysis patients,even up to 55.6% in old patients .Recent study showed that hypokalemia is an risk factors of peritonitis. Voltage-gated potassium channel 1.3(Kvl.3) is one of pathways that potassium transports from intracellular to extracellular.The expression of Kvl.3 is abnormal in auto-immune disease.Blocking potassium channel selectively can alleviate or delay the development of disease. However,very little is known about the effect of peritonitis on the expression of Kvl.3 on peritoneal macrophage。Part 1:The serum potassium and the expression of Kv1.3 on peritoneal macrophages from continuous ambulatory peritoneal dialysis patients with peritonitisObjectives:To investigate serum potassium and the expression of Kvl.3 on peritoneal monocytes/macrophages from continuous ambulatory peritoneal dialysis patients with peritonitis.Methods:32 CAPD patients with peritonitis and 55 CAPD patients without peritonitis were enrolled in this study.Kv1.3 expression of macrophages in dialysate effluents and were analyzed by flow cytometry.Results:The average of control group and peritonitis group were 49.9±14.9 and 51.7±15.3 years old receptively,male female ratio of two groups were 37:15and 17:15 receptively;the percentage of diabetic nephropathy of two group were 24% and 19% receptively; the average of peritoneal dialysis duration of two groups were 23.50±44.7 and 17.8±23.7 month. Compared with control group, the white cell/ neutrophilic granulocyte percentage/red cell/hemoglobin/serum potassium in control group were significant difference (P<0.01or P<0.05), serum albumin were not significant difference. Hypokalemia was found in patients with lower serum albumin and low BUN. The Mean Fluorescence intensity(MFI) of Kvl.3 in peritoneal macrophages of control subjects and patients with peritonitis were 9.54±3.61vs8.78±0.30 (P>0.05)。There was no correlation between serum potassium level and expression of Kvl.3 on peritoneal macrophage.Conclusions. The serum potassium was decreased significantly in patients with peritonitis compared with patients without peritonitis, which suggested that hypokalemia may be involved in peritonitis.However, it worthy to investigate whether hypokalemia increased the prevalence of peritonitis or not through following up. In additional, the abnormal Kv1.3 expression was not found in peritoneal macrophage, however, it is worth to study the Kvl.3 expression in peripheral blood monocytesPart 2:Effects of low potassium concentration medium on macrophagesObjectives:To investigate the effects of low potassium concentration medium on macrophagesMethods:Raw264.7 macrophage was cultured in RPMI1640 medium supplemented with 10% Fetal Bovine Serum (FBS).Cells were divided into 4 different groups: 5.4mM potassium medium group(control group),2mM potassium medium group,4mM potassium medium group and 10mM potassium medium group. Cell viability/phagocytic/bacteridal/inflammatory cytokines were measured.Results:In Raw264.7.cells viability of 4,8,12,24h of different potassium concentration treatment (5.4mMpotassium medium,2mM potassium medium,4mM potassium medium and 10mM potassium medium) were 95.49%±2.98%,96.00%±2.97%,95.51%±2.06%,96.79%±3.75%,93.20%±3.81%,92.40%±5.65%,92.9%±7.83%,93.7%±6.01%,91.9%±3.09%,87.76%±4.84%,89.2%±3.82%,93.94%±293%,88.74±2.72%,80.49%±1.67%;79.35%±9.58%,89.30%±5.77% respectively.After stimulation with different potassium concentration medium for 4h,the optical density (OD)that phagocytosis of neutral red assay of Raw264.7 were 0.21±0.02,0.15±0.01,0.19±0.01,0.22±0.01 respectively.The OD of 2mM group is significant lower than others',4mM's significant lower than 10mM's. The different number of bacteria (cfu) in T-0 and T-90 after different potassium medium treatment were18.89±6.72x104,10.56±1.8×104,13.31±6.50×104,27.23±9.24x104; 12.92±5.32×10,5.64±2.53×104,9.42×7.05×104,17.64±5.64×104 respectively. The killing bacteria ability of 2mM was significant lower than 5.4mM and 10mM,meanwhile,4mM was significant than lOmM.In additional,Raw264.7 were stimulated with different potassium medium for 4h,and then incubated with LPS for 4h,the frequency of IL-6 expression cells were 30.37±6.37.21.37±223,27.83±3.34,33.85±3.85 respectively,2mM was significant lower than other,4mM was significant lower than 5.4mM and lOmM The median of frequency of TNF-a expression and were 98.65,97.770,97.3,97.23 respectively.Conclusions:The low potassium concentration medium can inhibit the phagocytosis and bactericidal activity of Raw264.7 cells and inhibit LPS-induced the inflammatory factor, meanwhile, high extracellular potassium concentration can promote the phagocytosis and bactericidal activity of Raw264.7 cells.Summaryl.The serum potassium level was decreased in PD patients with peritonitis and the abnormal expression of Kvl.3 on macrophage was not found. It suggested that hypokalemia may be involved in peritonitis. However, it worthy to investigate whether hypokalemia increased the prevalence of peritonitis or not through follow up. In additional, the abnormal Kv1.3 expression was not found in peritoneal macrophage, however, it is worth to study the Kvl.3 expression in peripheral blood monocytes2.The low potassium concentration can inhibit the function of Raw264.7 cells.