Inhibitory effects of blocking voltage-dependent potassium channel 1.3 on human monocyte-derived macrophage differentiation into foam cells.
OBJECTIVE
To investigate the expression of voltage-dependent potassium channel 1.3 (Kv1.3) mRNA and protein during human monocyte-derived macrophage differentiation into foam cells and its function in foam cell formation.


METHODS
Human peripheral blood monocytes were isolated from healthy male volunteers by density gradient centrifugation and then by adherent method. The obtained monocytes were cultured for 5 days to differentiate into macrophages. Based on establishment of the human macrophage-derived foam cell model, the expression of Kv1.3 channel was investigated by immunocytochemical staining, reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. Furthermore, the effects of rMargatoxin, a Kv 1.3 channel-specific inhibitor, on cholesterol metabolism in macrophages incepting oxidized low density lipoprotein (OxLDL) were studied.


RESULTS
After the macrophages co-incubated with 30 mg/L OxLDL at 37 degrees C for 60 hours, the cellular volume obviously enlarged and many red lipid granules were deposited in cytoplasm. The total amount of cholesterol (TC), free cholesterol (FC) and cholesterol ester (CE) in cells markedly increased and the ratio of CE/TC rose from (14.4+/-6.8)% to (57.9+/-3.5)% (n=7, P<0.05). However, the expression of Kv1.3 channel had no significant change. rMargatoxin (0.1 nmol/L and 10 nmol/L) markedly reduced the contents of TC, FC and CE in macrophages and the ratios of CE/TC decreased to (42.8+/-11.6)% and (22.6+/-8.0)%, respectively (n=7, P<0.05). Meanwhile, the red lipid granules deposited in the cytoplasm of macrophages also decreased.


CONCLUSIONS
These data clearly show that the expression of Kv1.3 channel does not change obviously during human monocyte-derived macrophage differentiation into foam cells and the blocking of it would prevent foam cell formation.
Lei
Xin-jun
XJ
Department of Cardiology, The First Affiliated Hospital of Medical School, Xi'an Jiaotong University, Xi'an 710061, China.
Ma
Ai-qun
AQ
Xi
Yu-tao
YT
Zhang
Wei
W
Yao
Yan
Y
Du
Yuan
Y
D000328:Adult; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D005487:Foam Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D051664:Kv1.3 Potassium Channel / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009000:Monocytes / Q000166:cytology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012604:Scorpion Venoms / Q000494:pharmacology
D051664:Kv1.3 Potassium Channel; D026902:Potassium Channel Blockers; D012333:RNA, Messenger; D012604:Scorpion Venoms; C077910:margatoxin; D002784:Cholesterol