ABSTRACT
Interest in foods that promote inner beauty increases with increases in exposure to ultraviolet (UV) rays and with improvements in quality of life. This study was performed to evaluate the efficacy of fermented and aged mountain-cultivated ginseng sprouts (FAMCGSs), which have higher anti-inflammatory and antioxidant effects compared to mountain-cultivated ginseng sprouts (MCGSs), as an inner beauty enhancing food. The effect of orally administered FAMCGSs on UV type B (UVB) radiation-induced skin aging was investigated in a hairless mouse model through analyzing skin parameters including epidermal thickness, transepidermal water loss (TEWL), roughness, moisture, elasticity, and collagen contents. The mice exposed to UVB had markedly greater epidermal thickness, TEWL, and skin roughness than those of the normal control (NC) group. In addition, the levels of collagen, skin moisture, and dermal elasticity were lower in the UVB radiation group than the NC group. These UVB-induced skin aging parameters were significantly lower in the groups administered FAMCGSs than in the groups not administered FAMCGSs (p < 0.05). These results show that FAMCGSs exhibit a photoprotective effect in mice exposed to UVB and suggest that FAMCGSs can be used as a food that promotes inner beauty and protects skin from UVB-induced photoaging.
Subject(s)
Panax , Skin Aging , Animals , Mice , Ultraviolet Rays/adverse effects , Mice, Hairless , Quality of Life , Skin , Collagen/pharmacology , Plant Extracts/pharmacologyABSTRACT
This study investigated changes in nutrients (fatty acids, amino acids, and minerals), ginsenosides, and volatile flavors, and antioxidant activities during food processing of mountain-cultivated ginseng (MCG) with the cocktail lactic acid bacteria. Fatty acid content increased, but the free amino acid content decreased, and minerals were practically unaffected during processing. Total phenolic and flavonoid contents and maillard reaction products increased markedly according to processing stage. The total ginsenosides levels increased from 31.25 mg/g (DMCG) to 32.36 mg/g (red MCG, RMCG) and then decreased (27.27 mg/g, at fermented RMCG) during processing. Particularly, the contents of F2 (0.31 â 1.02 â 2.27 mg/g), Rg3 (0.36 â 0.77 â 1.93 mg/g), and compound K (0.5 â 1.68 â 4.13 mg/g) of ginsenosides and ß-panasinsene (17.28 â 22.69 â 31.61%), biocycloelemene (0.11 â 0.84 â 0.92%), δ-cadinene (0.39 â 0.5 â 0.94%), and alloaromadendrene (1.64 â 1.39 â 2.6%) of volatile flavor compounds increased during processing, along with to the antioxidant effects (such as DPPH, ABTS, and hydroxyl radical scavenging activities, and FRAP). This study may provide several choices for the use of ginseng in functional foods and functional cosmetics.
Subject(s)
Ginsenosides , Panax , Antioxidants/chemistry , Ginsenosides/chemistry , Hydroxyl Radical/chemistry , Panax/chemistry , Phenols/chemistryABSTRACT
The aim of this study is to explore anti-inflammatory phytochemicals from B. chinensis based on the inhibition of pro-inflammatory enzyme, human neutrophil elastase (HNE) and anti-inflammatory activities in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage. Three stereoisomers of iridal-type triterpenoids (1-3) were isolated from the roots of B. chinensis and their stereochemistries were completely identified by NOESY spectra. These compounds were confirmed as reversible noncompetitive inhibitors against HNE with IC50 values of 6.8-27.0 µM. The binding affinity experiment proved that iridal-type triterpenoids had only a single binding site to the HNE enzyme. Among them, isoiridogermanal (1) and iridobelamal A (2) displayed significant anti-inflammatory effects by suppressing the expressions of pro-inflammatory cytokines, such as iNOS, IL-1ß, and TNF-α through the NF-κB pathway in LPS-stimulated RAW264.7 cells. This is the first report that iridal-type triterpenoids are considered responsible phytochemicals for anti-inflammatory effects of B. chinensis.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Iridaceae/chemistry , Leukocyte Elastase/antagonists & inhibitors , Plant Extracts/pharmacology , Triterpenes/pharmacology , Animals , Anti-Inflammatory Agents/chemistry , Anti-Inflammatory Agents/isolation & purification , Cell Survival/drug effects , Cells, Cultured , Humans , Leukocyte Elastase/metabolism , Lipopolysaccharides/antagonists & inhibitors , Lipopolysaccharides/pharmacology , Mice , Molecular Conformation , NF-kappa B/antagonists & inhibitors , NF-kappa B/metabolism , Plant Extracts/chemistry , Plant Extracts/isolation & purification , RAW 264.7 Cells , Triterpenes/chemistry , Triterpenes/isolation & purificationABSTRACT
Depression is more common in women with breast cancer than the general population. Selective serotonin reuptake inhibitors (SSRIs), a group of antidepressants, are widely used for the treatment of patients with depression and a range of anxiety-related disorders. The association between the use of antidepressant medication and breast cancer is controversial. In this study, we investigated whether and how SSRIs induce the death of human breast cancer MCF-7 cells. Of the antidepressants tested in this study (amitriptyline, bupropion, fluoxetine, paroxetine, and tianeptine), paroxetine most reduced the viability of MCF-7 cells in a time-and dose-dependent manner. The exposure of MCF-7 cells to paroxetine resulted in mitochondrion-mediated apoptosis, which is assessed by increase in the number of cells with sub-G1 DNA content, caspase-8/9 activation, poly (ADP-ribose) polymerase cleavage, and Bax/Bcl-2 ratio and a reduction in the mitochondrial membrane potential. Paroxetine increased a generation of reactive oxygen species (ROS), intracellular Ca2+ levels, and p38 MAPK activation. The paroxetine-induced apoptotic events were reduced by ROS scavengers and p38 MAPK inhibitor, and the paroxetine's effect was dependent on extracellular Ca2+ level. Paroxetine also showed a synergistic effect on cell death induced by chemotherapeutic drugs in MCF-7 and MDA-MB-231 cells. Our results showed that paroxetine induced apoptosis of human breast cancer MCF-7 cells through extracellular Ca2+-and p38 MAPK-dependent ROS generation. These results suggest that paroxetine may serve as an anticancer adjuvant to current cancer therapies for breast cancer patients with or without depression.
ABSTRACT
Garlic (Allium sativum) has been used as a medicinal food since ancient times. However, some people are reluctant to ingest raw garlic due to its unpleasant odor and taste. Therefore, many types of garlic preparations have been developed to reduce these attributes without losing biological functions. Aged black garlic (ABG) is a garlic preparation with a sweet and sour taste and no strong odor. It has recently been introduced to Asian markets as a functional food. Extensive in vitro and in vivo studies have demonstrated that ABG has a variety of biological functions such as antioxidant, anti-inflammatory, anti-cancer, anti-obesity, anti-diabetic, anti-allergic, cardioprotective, and hepatoprotective effects. Recent studies have compared the biological activity and function of ABG to those of raw garlic. ABG shows lower anti-inflammatory, anti-coagulation, immunomodulatory, and anti-allergic effects compared to raw garlic. This paper reviews the physicochemical properties, biological activity, health benefits, adverse effects, and general limitations of ABG.
Subject(s)
Garlic/chemistry , Phytochemicals/chemistry , Phytochemicals/pharmacology , Plant Extracts/chemistry , Plant Extracts/pharmacology , Animals , Anti-Inflammatory Agents/chemistry , Anti-Inflammatory Agents/pharmacology , Antioxidants/chemistry , Antioxidants/pharmacology , Biomarkers , Cell Line , Cytokines/metabolism , Humans , Inflammation Mediators/metabolism , Macrophages/drug effects , Macrophages/immunology , Macrophages/metabolism , Mice , Nitric Oxide/metabolismABSTRACT
Numerous studies have demonstrated that aged black garlic (ABG) has strong anti-oxidant activity. Little is known however regarding the anti-inflammatory activity of ABG. This study was performed to identify and compare the anti-oxidant and anti-inflammatory effects of ABG extract (ABGE) with those of fresh raw garlic (FRG) extract (FRGE). In addition, we investigated which components are responsible for the observed effects. Hydrogen peroxide (H2O2) and lipopolysaccharide (LPS) were used as a pro-oxidant and pro-inflammatory stressor, respectively. ABGE showed high ABTS and DPPH radical scavenging activities and low ROS generation in RAW264.7 cells compared with FRGE. However, inhibition of cyclooxygenase-2 and 5-lipooxygenase activities by FRGE was stronger than that by ABGE. FRGE reduced PGE2, NO, IL-6, IL-1ß, LTD4, and LTE4 production in LPS-activated RAW264.7 cells more than did ABGE. The combination of FRGE and sugar (galactose, glucose, fructose, or sucrose), which is more abundant in ABGE than in FRGE, decreased the anti-inflammatory activity compared with FRGE. FRGE-induced inhibition of NF-κB activation and pro-inflammatory gene expression was blocked by combination with sugars. The lower anti-inflammatory activity in ABGE than FRGE could result from the presence of sugars. Our results suggest that ABGE might be helpful for the treatment of diseases mediated predominantly by ROS.
Subject(s)
Anti-Inflammatory Agents/chemistry , Garlic/chemistry , Inflammation/drug therapy , Plant Extracts/chemistry , Animals , Anti-Inflammatory Agents/administration & dosage , Antioxidants/administration & dosage , Antioxidants/chemistry , Cell Line , Humans , Hydrogen Peroxide/toxicity , Inflammation/chemically induced , Lipopolysaccharides/toxicity , Mice , Plant Extracts/administration & dosage , Reactive Oxygen Species/metabolismABSTRACT
Lipopolysaccharides (LPS) activate nuclear factor kappa B (NF-κB), a transcription factor that is involved in inflammatory response. The pathways that activate NF-κB can be modulated by phytochemicals derived from garlic. We recently demonstrated that aged red garlic extract (ARGE), a new formulation of garlic, decreases nitric oxide (NO) generation by upregulating of heme oxygenase-1 (HO-1) in RAW 264.7 cells activated by LPS. However, the effects of ARGE on LPS-induced NF-κB activation are unknown. This study was performed to evaluate whether ARGE regulates LPS-induced NO production by modulation of NF-κB activation in macrophages. The inhibition of NF-κB by Bay 11-7085, an inhibitor of NF-κB, decreased LPS-induced NO production. ARGE treatment markedly reduced LPS-induced NO production and NF-κB nuclear translocation. ARGE downregulated expression of inducible nitric oxide synthase (iNOS) and upregulated expression of HO-1, a cytoprotective and anti-inflammatory protein. However, Bay 11-7085 only reduced iNOS expression. The NO production and iNOS expressions upregulated by suppression of HO-1 were suppressed by treatment with ARGE and Bay 11-7085. These results show that ARGE reduces LPS-induced NO production in macrophages through inhibition of NF-κB nuclear translocation and HO-1 activation. Compared to Bay 11-7085, ARGE may enhance anti-inflammatory effects by controlling other anti-inflammatory signals as well as regulation of NF-κB.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Garlic/chemistry , Macrophages/drug effects , NF-kappa B/immunology , Nitric Oxide/immunology , Plant Extracts/pharmacology , Animals , Down-Regulation/drug effects , Heme Oxygenase-1/genetics , Heme Oxygenase-1/immunology , Humans , Lipopolysaccharides/immunology , Lipopolysaccharides/pharmacology , Macrophages/enzymology , Macrophages/immunology , Mice , NF-kappa B/genetics , Nitric Oxide Synthase Type II/genetics , Nitric Oxide Synthase Type II/immunology , RAW 264.7 CellsABSTRACT
Garlic has a variety of biologic activities, including anti-inflammatory properties. Although garlic has several biologic activities, some people dislike eating fresh raw garlic because of its strong taste and smell. Therefore, garlic formulations involving heating procedures have been developed. In this study, we investigated whether short-term heating affects the anti-inflammatory properties of garlic. Fresh and heated raw garlic extracts (FRGE and HRGE) were prepared with incubation at 25 °C and 95 °C, respectively, for 2 h. Treatment with FRGE and HRGE significantly reduced the LPS-induced increase in the pro-inflammatory cytokine concentration (TNF-α, IL-1ß, and IL-6) and NO through HO-1 upregulation in RAW 264.7 macrophages. The anti-inflammatory effect was greater in FRGE than in HRGE. The allicin concentration was higher in FRGE than in HRGE. Allicin treatment showed reduced production of pro-inflammatory cytokines and NO and increased HO-1 activity. The results show that the decrease in LPS-induced NO and pro-inflammatory cytokines in RAW 264.7 macrophages through HO-1 induction was greater for FRGE compared with HRGE. Additionally, the results indicate that allicin is responsible for the anti-inflammatory effect of FRGE. Our results suggest a potential therapeutic use of allicin in the treatment of chronic inflammatory disease.
Subject(s)
Cytokines/biosynthesis , Down-Regulation/drug effects , Garlic/chemistry , Hot Temperature , Inflammation Mediators/metabolism , Lipopolysaccharides/pharmacology , Macrophages/drug effects , Nitric Oxide/biosynthesis , Plant Extracts/pharmacology , Sulfinic Acids/metabolism , Animals , Cell Line , Disulfides , Macrophages/metabolism , MiceABSTRACT
Ischemia-reperfusion injury is a phenomenon that occurs when tissues are subjected to ischemia for a variable period of time, and then reperfused. Inflammatory reaction has been implicated as one of the most important mechanism of ischemia-reperfusion injury. The purpose of this study was to evaluate the anti-inflammatory effects of anthocyanins from black soybean seed coat on keratinocytes in vitro and ischemia-reperfusion injury in vivo. We investigated the inhibition, by anthocyanins, of the expression of various inflammatory genes associated with ischemia-reperfusion injury in the tumor necrosis factor-alpha-treated (TNF-α) immortalized epidermal keratinocyte cell line (HaCaT). We also investigated the effects of anthocyanins on the survival of skin flaps after ischemia-reperfusion injury in the rats. According to Western blot analysis and a luciferase activity assay, anthocyanins inhibited TNF-α-induced intercellular adhesion molecule-1 and cyclooxygenase-2 (COX-2) levels through the NF-κB-dependent pathway. Administration of anthocyanins (50 and 100 mg/kg) significantly improved the flap area survival in the 10-hour ischemic model from 62% to 74.5% and 83%, respectively (P = 0.001). The related cytokines in skin flap also changed as the same pattern as in vitro. Our results indicate that anthocyanins from black soybean seed coat had anti-inflammatory effects on the HaCaT cell line and increase the survival of skin flaps through anti-inflammatory properties against ischemia-reperfusion injury.
Subject(s)
Anthocyanins/pharmacology , Glycine max , Keratinocytes/drug effects , Phytotherapy , Plant Extracts/pharmacology , Reperfusion Injury/prevention & control , Surgical Flaps/blood supply , Animals , Anthocyanins/therapeutic use , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Biomarkers/metabolism , Blotting, Western , Cell Line , Cytokines/metabolism , Graft Survival , Keratinocytes/metabolism , Male , Plant Extracts/therapeutic use , Random Allocation , Rats , Rats, Sprague-Dawley , SeedsABSTRACT
Increasing antioxidant capacity has been proposed as a promising strategy to prevent cigarette smoke-induced lung diseases. This study tested whether garlic extracts prevented cigarette smoke extract (CSE)-induced cell death in human bronchial smooth muscle cells (HBSMCs). Garlic extracts were prepared from fresh raw garlic (FRG), aged black garlic (ABG) and aged red garlic (ARG). Treatment of HBSMCs with 10% CSE induced cell death accompanied by activation of caspase. Of the garlic extracts, treatment with ARG extract reduced CSE-induced cell death. The combination of ARG extract with CSE attenuated the CSE-induced reduction in glutathione (GSH) content, generation of reactive oxygen species (ROS) and induction of heme oxygenase-1 expression compared with CSE treatment without ARG extract. Furthermore, the combination of L-BSO, a GSH synthesis inhibitor, with ARG and CSE extracts failed to increase the intracellular GSH content and cell viability. Taken together, these results demonstrate that ARG extract reduces CSE-induced cell death by increasing GSH content and reducing ROS generation in HBSMCs.
Subject(s)
Allium , Antioxidants/pharmacology , Bronchi/drug effects , Glutathione/metabolism , Muscle, Smooth/drug effects , Plant Extracts/pharmacology , Smoking/adverse effects , Antioxidants/therapeutic use , Bronchi/cytology , Bronchi/metabolism , Caspases/metabolism , Cell Death/drug effects , Cell Line , Heme Oxygenase-1/metabolism , Humans , Lung Diseases/etiology , Lung Diseases/prevention & control , Muscle Cells/drug effects , Muscle, Smooth/cytology , Muscle, Smooth/metabolism , Phytotherapy , Plant Extracts/therapeutic use , Reactive Oxygen Species/metabolism , Smoke/adverse effectsABSTRACT
Various methods have been used to remove reactive oxygen species (ROS) generated from in vitro culture (IVC) conditions that can cause cell injury or death, including the application of low oxygen (O(2)) tension and the addition of antioxidants. The beneficial effects of antioxidants and O(2) tension on IVC of porcine embryos, however, are controversial among researchers. In this study, we sought to determine the effects and optimal concentrations of antioxidants for the development of porcine embryos in an IVC system. Specifically, we examined the synergistic effects of antioxidants on development to the blastocyst stage in a culture system supplemented with L-cysteine during IVM. Of the antioxidants tested (melatonin, glutathione (GSH), ß-mercaptoethanol (ß-ME), N-acetylcysteine (NAC) and dithiothreitol (DTT)), addition of GSH (1 mM) or ß-ME (25 µM) significantly increased development to the blastocyst stage compared with the controls without antioxidant treatment (22.2 ± 4.2% for 1 mM GSH, 25.9 ± 2.2% for 25 µM ß-ME and 12-13% for the control, P<0.05). In addition, the mean cell number per blastocyst was increased by approximately 1.7-fold in the presence of GSH or ß -ME. These GSH- and ß-ME-induced increases in development to the blastocyst stage and total cell number, however, were not mimicked by melatonin, NAC or DTT, all of which are ROS scavengers. The combination of GSH or ß-ME with L-cysteine significantly reduced high O(2) tension-induced ROS production (P<0.05). These results suggest that a combination of 1 mM GSH or 25 µM ß-ME with 1 mM L-cysteine could be used for production of high quality porcine blastocysts in IVC systems.
Subject(s)
Antioxidants/pharmacology , Blastocyst/drug effects , Cysteine/metabolism , Ectogenesis/drug effects , Embryo Culture Techniques/veterinary , Oocytes/drug effects , Sus scrofa/embryology , Animal Husbandry , Animals , Blastocyst/cytology , Blastocyst/metabolism , Cell Count , Drug Synergism , Female , Fertilization in Vitro/methods , Fertilization in Vitro/veterinary , Glutathione/pharmacology , Male , Mercaptoethanol/pharmacology , Oocytes/cytology , Oocytes/metabolism , Osmolar Concentration , Oxidative Stress/drug effects , Oxygen/metabolism , Reactive Oxygen Species/metabolism , Sus scrofa/metabolismABSTRACT
Insulin secretion from pancreatic beta cells is partly regulated by cell membrane potential. Background K+ channels that stabilize the resting membrane potential would suppress excitability and insulin secretion. Recent studies show that members of the two-pore domain K+ (K2P) channel family behave as background K+ channels in many excitable cells. Therefore, the expression of K2P channels was studied in insulin-secreting MIN6 cells. Reverse transcriptase PCR showed that, among nine K2P channels tested, TASK-1, TASK-2, TASK-3, TREK-2, and TRESK-2 were expressed in MIN6 cells. Cell-attached recordings on MIN6 cells revealed five types of K+ channels that were open at rest. Two were ATP-sensitive and Ca2+-activated K+ channels, as judged by their sensitivity to ATP and Ca2+, respectively, and single-channel conductance. Among five K2P channels, only TREK-2 could be clearly identified in MIN6 cells. The molecular identity of two other K+ channels is not yet known. TREK-2 in MIN6 cells was activated by arachidonic acid, membrane stretch, and low pH solution (pH 5.8). Arachidonic acid increased Ba2+-sensitive whole-cell current in MIN6 cell. These results suggest that TREK-2 contributes to the background K+ conductance in MIN6 cells, and may regulate depolarization-induced secretion of insulin.
Subject(s)
Insulin/metabolism , Potassium Channels/biosynthesis , Adenosine Triphosphate/chemistry , Animals , Arachidonic Acid/chemistry , Arachidonic Acid/metabolism , Barium/chemistry , COS Cells , Calcium/metabolism , Cell Line , Cloning, Molecular , DNA Primers/chemistry , DNA, Complementary/metabolism , Electrophysiology , Hydrogen-Ion Concentration , Membrane Potentials , Mice , Potassium/chemistry , Potassium Channels, Tandem Pore Domain , Reverse Transcriptase Polymerase Chain Reaction , TransfectionABSTRACT
A new member of the tandem-pore K+ (K(2P)) channel family has been isolated from mouse testis complementary DNA. The new K(2P) channel was named TRESK-2, as its amino acid sequence shares 65% identity with that of TRESK-1. Mouse TRESK-2 is a 394-amino acid protein and possesses four putative transmembrane segments and two pore-forming domains. TRESK-2 has a long cytoplasmic domain joining the second and third transmembrane segments and a short carboxyl terminus. In the rat, TRESK-2 mRNA transcripts were expressed abundantly in the thymus and spleen and at low levels in many other tissues, including heart, small intestine, skeletal muscle, uterus, testis, and placenta, as judged by Northern blot analysis. TRESK-2 mRNA was also expressed in mouse and human tissues. In COS-7 cells transfected with TRESK-2 DNA, a time-independent and noninactivating K+-selective current was recorded. TRESK-2 was insensitive to 1 mm tetraethylammonium, 100 nm apamin, 1 mm 4-aminopyridine, and 10 microm glybenclamide. TRESK-2 was inhibited by 10 microm quinidine, 20 microm arachidonate and acid (pH 6.3) at 49, 43, and 23%, respectively. Single channel openings of TRESK-2 showed marked open channel noise. In symmetrical 150 mm KCl, the current-voltage relationship of TRESK-2 was slightly inwardly rectifying, with the single channel conductance 13 picosiemens (pS) at +60 mV and 16 pS at -60 mV. In inside-out patches, TRESK-2 was unaffected by the intracellular application of 10 microm guanosine 5'-O-(thiotriphosphate). These results show that TRESK-2 is a functional member of the K(2P) channel family and contributes to the background K+ conductance in many types of cells.
Subject(s)
Potassium Channels/biosynthesis , 4-Aminopyridine/pharmacology , Amino Acid Sequence , Animals , Apamin/pharmacology , Arachidonic Acid/pharmacology , Base Sequence , Blotting, Northern , COS Cells , Cell Membrane/metabolism , Cloning, Molecular , Cytoplasm/metabolism , DNA/chemistry , DNA, Complementary/metabolism , Electrophysiology , Glyburide/pharmacology , Humans , Male , Mice , Molecular Sequence Data , Phylogeny , Potassium Channels/chemistry , Protein Structure, Tertiary , RNA, Messenger/metabolism , Rats , Reverse Transcriptase Polymerase Chain Reaction , Sequence Homology, Amino Acid , Testis/metabolism , Tetraethylammonium/pharmacology , Time Factors , Tissue Distribution , TransfectionABSTRACT
TASK-1 and TASK-3 are functional members of the tandem-pore K+ (K2P) channel family, and mRNAs for both channels are expressed together in many brain regions. Although TASK-1 and TASK-3 subunits are able to form heteromers when their complementary RNAs are injected into oocytes, whether functional heteromers are present in the native tissue is not known. Using cultured cerebellar granule (CG) neurones that express mRNAs of both TASK-1 and TASK-3, we studied the presence of heteromers by comparing the sensitivities of cloned and native K+ channels to extracellular pH (pHo) and ruthenium red. The single-channel conductance of TASK-1, TASK-3 and a tandem construct (TASK-1/TASK-3) expressed in COS-7 cells were 14.2 +/- 0.4, 37.8 +/- 0.7 and 38.1 +/- 0.7 pS (-60 mV), respectively. TASK-3 and TASK-1/TASK-3 (and TASK-3/TASK-1) displayed nearly identical single-channel kinetics. TASK-3 and TASK-1/TASK-3 expressed in COS-7 cells were inhibited by 26 +/- 4 and 36 +/- 2 %, respectively, when pHo was changed from 8.3 to 7.3. In outside-out patches from CG neurones, the K+ channel with single channel properties similar to those of TASK-3 was inhibited by 31 +/- 7 % by the same reduction in pHo. TASK-3 and TASK-1/TASK-3 expressed in COS-7 cells were inhibited by 78 +/- 7 and 3 +/- 4 %, respectively, when 5 microm ruthenium red was applied to outside-out patches. In outside-out patches from CG neurones containing a 38 pS channel, two types of responses to ruthenium red were observed. Ruthenium red inhibited the channel activity by 77 +/- 5 % in 42 % of patches (range: 72-82 %) and by 5 +/- 4 % (range: 0-9 %) in 58 % of patches. When patches contained more than three 38 pS channels, the average response to ruthenium red was 47 +/- 6 % inhibition (n= 5). These electrophysiological studies show that native 38 pS K+ channels of the TASK family in cultured CG neurones consist of both homomeric TASK-3 and heteromeric TASK-1/TASK-3.