BACKGROUNDKetanserin (KT), a selective serotonin (5-HT) 2-receptor antagonist, reduces peripheral blood pressure by blocking the activation of peripheral 5-HT receptors. In this study electrophysiological method was used to investigate the effect of KT and potassium ion on Kv1.3 potassium channels and explore the role of blocker KT in the alteration of channel kinetics contributing to the potassium ion imbalances.

METHODSKv1.3 channels were expressed in xenopus oocytes, and currents were measured using the two-microelectrode voltage-clamp technique.

RESULTSKCl made a left shift of activation and an inactivation curve of Kv1.3 current and accelerated the activation and inactivation time constant. High extracellular [K(+)] attenuated the blockade effect of KT on Kv1.3 channels. In the presence of KT and KCl the activation and inactivation time constants were not influenced significantly no matter what was administered first. KT did not significantly inhibit Kv1.3 current induced by tetraethylammonium (TEA).

CONCLUSIONSKT is a weak blocker of Kv1.3 channels at different concentrations of extracellular potassium and binds to the intracellular side of the channel pore. The inhibitor KT of ion channels is not fully effective in clinical use because of high [K(+)](o) and other electrolyte disorders.

Animals ; Electrophysiology ; Female ; Ketanserin ; pharmacology ; Kv1.3 Potassium Channel ; drug effects ; metabolism ; Oocytes ; Patch-Clamp Techniques ; Potassium ; pharmacology ; Serotonin Antagonists ; pharmacology ; Xenopus laevis

OBJECTIVETo investigate the effect of diclofenac on the expression of Kv1.3 and Kir2.1 channels in human macrophages and the membrane potential and foaming process of the macrophages.

METHODSThe effect of diclofenac on the expression of Kv1.3 and Kir2.1 channels in cultured human monocyte-derived macrophages was investigated using real-time RT-PCR and Western blotting, and its effect on the membrane potential was analyzed with optical mapping of the membrane potential with voltage-sensitive dyes. The ratio of cholesterol ester (CE) in the macrophages following intake of oxidized low-density lipoprotein (OxLDL) was analyzed by an enzymatic fluorometric method.

RESULTSThe expression of Kv1.3 and Kir2.1 channels in the macrophages were down-regulated by diclofenac (1.5 µmol/L and 15 µmol/L). Compared with those in the control group, Kv1.3 mRNA expression was reduced by over 80% and 90% (P<0.05), and Kir2.1 mRNA by over 20% and 30% (P>0.05), respectively; both their protein expression was reduced by over 10% and 60% with a dose- dependent effect (P<0.05). Diclofenac at the two doses dose-dependently reduced the surface fluorescence intensity of the macrophage, and the membrane potential was decreased by 28% and 54%, respectively (P<0.05). Incubation of the macrophages with 30 mg/L OxLDL for 60 h caused an obvious enlargement of the cell volume and deposition of numerous lipid granules in cytoplasm, resulting also in a CE/TC ratio over 50% (P<0.05). Diclofenac at 1.5 and 15 µmol/L both significantly decreased the CE/TC ratio to (23.624∓3.34)% and (13.601∓2.916)% (P<0.05), respectively, but this effect did not show a dose-response relationship (P>0.05).

CONCLUSIONDiclofenac can significant down-regulate the expression of Kv1.3 and Kir2.1 channels in human macrophages, lower their membrane potential and inhibit the process of foam cell formation.

Cells, Cultured ; Diclofenac ; pharmacology ; Foam Cells ; cytology ; drug effects ; Humans ; Kv1.3 Potassium Channel ; metabolism ; Macrophages ; drug effects ; metabolism ; physiology ; Membrane Potentials ; drug effects ; Potassium Channels, Inwardly Rectifying ; metabolism

BACKGROUNDThe cell layer of the ciliary epithelium is responsible for aqueous humor secretion and maintenance. Ion channels play an important role in these processes. The main aim of this study was to determine whether the well-characterized members of the Kv1 family (Kv1.3) contribute to the Kv currents in ciliary epithelium.

METHODSNew Zealand White rabbits were maintained in a 12 hours light/dark cycle. Ciliary epithelium samples were isolated from the rabbits. We used Western blotting and immunocytochemistry to identify the expression and location of a voltage-gated potassium channel Kv1.3 in ciliary body epithelium. Membrane potential change after adding of Kv1.3 inhibitor margatoxin (MgTX) was observed with a fluorescence method.

RESULTSWestern blotting and immunocytochemical studies showed that the Kv1.3 protein expressed in pigment ciliary epithelium and nonpigment ciliary epithelium, however it seemed to express more in the apical membrane of the nonpigmented epithelial cells. One nmol/L margatoxin, a specific inhibitor of Kv1.3 channels caused depolarization of the cultured nonpigmented epithelium (NPE) membrane potential. The cytosolic calcium increased after NPE cell depolarization, this increase of cytosolic calcium was partially blocked by 12.5 micromol/L dantrolene and 10 micromol/L nifedipine. These observations suggest that Kv1.3 channels modulate ciliary epithelium potential and effect calcium dependent mechanisms.

CONCLUSIONKv1.3 channels contribute to K+ efflux at the membrane of rabbit ciliary epithelium.

Animals ; Blotting, Western ; Calcium ; metabolism ; Ciliary Body ; cytology ; metabolism ; physiology ; Immunohistochemistry ; In Vitro Techniques ; Kv1.3 Potassium Channel ; metabolism ; physiology ; Membrane Potentials ; physiology ; Pigment Epithelium of Eye ; cytology ; metabolism ; physiology ; Rabbits

The present study aimed to investigate the difference in the voltage dependent potassium channel (Kv) expression in lymphocytes between the spontaneously hypertensive rats (SHRs) and Wistar rats. Peripheral blood lymphocytes were collected from 10 male SHRs and 10 normotensive Wistar rats aged 16 weeks. First, by using the patch-clamp technique, Kv channel current was recorded in freshly isolated lymphocytes from SHRs and normotensive Wistar rats. Total RNAs were extracted from lymphocytes by using TRIzol reagent. Real-time PCR was used to determine the expression of Kv1.3 mRNA and Western blot technique was used to measure the expression of Kv1.3 protein in lymphocytes from SHRs and normotensive Wistar rats. The results showed that: (1) The current density of Kv channel in the step voltage of +60 mV was higher in lymphocytes from SHRs than that from the normotensive Wistar rats [(119+/-10) pA/pF vs (56+/-9) pA/pF, P<0.05]; (2) The level of Kv1.3 mRNA expression in lymphocytes from SHRs was significantly increased compared with that of the normotensive Wistar rats (0.0313+/-0.017 vs 0.0023+/-0.005, P<0.05); (3) The expression of Kv1.3 protein was significantly elevated in lymphocytes (1.02+/-0.04 vs 0.41+/-0.03, P<0.05) from SHRs compared with that of the normotensive Wistar rats. The results obtained demonstrate that the lymphocytes Kv channels are increased in SHR, and the Kv channel may be involved in activation of lymphocytes from SHR.
Animals ; Hypertension ; metabolism ; Kv1.3 Potassium Channel ; genetics ; metabolism ; Lymphocytes ; metabolism ; Male ; Patch-Clamp Techniques ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Inbred SHR ; Rats, Wistar

OBJECTIVETo determine current density of voltage-gated potassium channels and Kv1.3 express in T-lymphocyte derived from patients with acute coronary syndrome (ACS).

METHODSPeripheral blood mononuclear cells were collected from 12 patients with ACS and 10 control donors. Whole-cell patch clamp technique was used to record the outward K(+) currents (IK) and western blots technique was used to detect the express of Kv1.3 protein in lymphocyte.

RESULTS(1) The current density of voltage-gated potassium channel was significantly higher in ACS patients [(269 +/- 94) pA/pF] than in controls [(191 +/- 64) pA/pF, P < 0.01] while membrane capacitance was similar between the two groups. (2) Kv1.3 protein expression was also significantly increased in ACS patients than in controls (P < 0.01).

CONCLUSIONThe lymphocyte voltage-gated potassium channel is upregulated in patients with ACS suggesting a role of Kv activation in the pathophysiology of ACS.

Acute Coronary Syndrome ; metabolism ; Adult ; Aged ; Female ; Humans ; Kv1.3 Potassium Channel ; metabolism ; Male ; Middle Aged ; Patch-Clamp Techniques ; T-Lymphocytes ; metabolism

This study was aimed to investigate the effects of blockade of Ca(2+) activated channel KCa3.1 and voltage-gated potassium channel Kv1.3 of the monocytes/macrophages on inflammatory monocyte chemotaxis. Chemotaxis assay was used to test the inflammatory Ly-6C(hi) monocyte chemotaxis caused by the monocytes/macrophages. The proliferation of monocytes/macrophages was detected by cell counting kit-8 (CCK8). Enzyme-linked immunosorbent assay (ELISA) was applied to detect the C-C motif ligand 7 (CCL7) in cultured media. The results showed that the recruitment of Ly-6C(hi) monocyte induced by monocytes/macrophages was suppressed by the potent Kv1.3 blocker Stichodactyla helianthus neurotoxin (ShK) or the specific KCa3.1 inhibitor TRAM-34. Meanwhile, the proliferation of monocytes/macrophages was significantly inhibited by ShK. The response of Ly-6C(hi) monocyte pretreated with ShK or TRAM-34 to CCL2 was declined. These results suggest that KCa3.1 and Kv1.3 may play an important role in monocytes/macrophages' proliferation and migration.
Cell Movement ; Cell Proliferation ; Cnidarian Venoms ; pharmacology ; Enzyme-Linked Immunosorbent Assay ; Humans ; Kv1.3 Potassium Channel ; antagonists & inhibitors ; physiology ; Macrophages ; cytology ; Monocytes ; cytology ; Protein Structure, Tertiary ; Pyrazoles ; pharmacology ; Small-Conductance Calcium-Activated Potassium Channels ; antagonists & inhibitors ; physiology

OBJECTIVE: To investigate the expression of Kv1.3 and Kir2.1 during human monocyte-derived macrophages differentiation into foam cells and their function in foam cells formation. METHODS: The human macrophage-derived foam cells were obtained by incubating macrophages with ox-LDL (30 mg/L) for 60 h. The expression of Kv1.3 and Kir2.1 channels were examined by immunocytochemistry, RT-PCR and Western blot. Effects of channel blockers (rMargatoxin and BaCl2) on the cellular cholesterol metabolism were studied by measuring the cellular contents of total cholesterol (TC), free cholesterol (FC), and cholesterol ester (CE) in the presence or absence of the channel blockers. RESULTS: After incubating macrophages with 30 mg/L ox-LDL for 60 h, the cellular contents of TC, FC and CE were markedly increased and the ratio of CE/TC was raised from (14.4+/-6.8)% to (57.9+/-3.5)% (P<0.05), which indicated that the cells had differentiated into foam cells. The expression of Kv1.3 and Kir2.1 channels appeared no obvious difference when differentiating into foam cells (P>0.05); After being blocked specifically (rMargatoxin: 0.1, 10 nmol/L; BaC(12): 75, 125 micromol/L), the cellular contents of TC and CE were markedly reduced without exception and the ratios of CE/TC were all less than 50% (P<0.05). CONCLUSION Both Kv1.3 and Kir2.1 channels play a critical role in differentiation of macrophages into foam cells and blockage of corresponding potassium channels would prevent the formation of the foam cells.
Barium Compounds ; pharmacology ; Cell Differentiation ; drug effects ; Cells, Cultured ; Chlorides ; pharmacology ; Cholesterol Esters ; metabolism ; Foam Cells ; cytology ; Humans ; Kv1.3 Potassium Channel ; antagonists & inhibitors ; Macrophages ; cytology ; Monocytes ; cytology ; Potassium Channels, Inwardly Rectifying ; antagonists & inhibitors ; Scorpion Venoms ; pharmacology