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1.
Eur Rev Med Pharmacol Sci ; 27(5): 1774-1792, 2023 03.
Article in English | MEDLINE | ID: mdl-36930472

ABSTRACT

OBJECTIVE: The aim of this study was to investigate the modular characteristics and mechanism of action of Chinese herbs for vascular calcification (VC) treatment. MATERIALS AND METHODS: Network pharmacology coupled with literature data mining was utilized to assess the Chinese herbal clinical performance as well as its similarity, characteristics, ingredient, target, and Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, and network construction. RESULTS: The top 15 medications from the literature, according to the usage, and 190 active chemicals, 183 common targets between medication and VC-related targets were weeded out. Analysis of the relationships between the active ingredients, pharmacological targets, and signaling pathways helped to clearly define the therapeutic effect of Traditional Chinese Medicine (TCM). Importantly, we discovered seven most hub proteins (AKT1, CTNNB1, TNF, EGFR, TP53, JUN and IL-6) and two of the herbs' most fundamental ingredients (Formononetin and Luteolin) in TCM-mediated VC suppression. Mechanistically, the metabolic pathways [AGE-RAGE pathway, interleukin-17 (IL-17) pathway, and p53 pathway] as well as smooth muscle adaptation (functional remodeling) and oxidoreductase activity (redox homeostasis modulating) are also crucially implicated. CONCLUSIONS: Our work, accomplished by network pharmacology and data mining, increases our understanding of TCM in VC therapy and may offer insightful information for future drug discovery investigations.


Subject(s)
Drugs, Chinese Herbal , Vascular Calcification , Humans , Medicine, Chinese Traditional , Network Pharmacology , Calcification, Physiologic , Data Mining , Drugs, Chinese Herbal/pharmacology , Drugs, Chinese Herbal/therapeutic use , Molecular Docking Simulation
2.
Zhonghua Jie He He Hu Xi Za Zhi ; 45(9): 930-935, 2022 Sep 12.
Article in Chinese | MEDLINE | ID: mdl-36097931

ABSTRACT

Pulmonary arterial hypertension is a progressive pulmonary vascular disease, which can cause right heart failure and even death in severe cases. Treprostinil is a stable prostacyclin analogue and a powerful drug for dilating pulmonary vessels. It can be administered in different ways, with a long half-life, good stability and is suited for diverse types of PAH. It is approved for the treatment of Group 1 PAH, but some studies show that treprostinil is effective in patients with Group 3 or Group 4 PAH. Therefore, this article will review the progress of evidence-based medicine evidence of traprostanil in the treatment of type 1, 3 and 4 pulmonary hypertension.


Subject(s)
Hypertension, Pulmonary , Antihypertensive Agents/therapeutic use , Epoprostenol/analogs & derivatives , Epoprostenol/therapeutic use , Familial Primary Pulmonary Hypertension , Humans , Hypertension, Pulmonary/drug therapy
3.
Mol Biol (Mosk) ; 51(4): 696-703, 2017.
Article in Russian | MEDLINE | ID: mdl-28900089

ABSTRACT

Epithelial-mesenchymal transition (EMT) and its reverse process mesenchymal-epithelial transition (MET) programs are involced in the metastatic process. More and more evidence confirms that EMT is vital for the initiation and dissemination of cancer cells whereas MET is critical for successful metastatic colonization of a secondary organ. The regulating mechanism of EMT mediated cancer progression and metastasis has been deeply investigated. However, what processes are dependent on MET in metastatic cascades remains unclear. Here, we created a cell based high-content siRNA screen using the breast cancer cell line 4TO7 to search for kinases that were involved in Git2-induced MET. Our results revealed that 58 kinases including transferase, phosphorylation regulators, ATP/nucleotide partners potentially participate in Git2-induced MET. Our preliminary data is expected to facilitate elucidation of the mechanism on how MET is initiated during cancer metastasis.


Subject(s)
Cell Cycle Proteins/pharmacology , Epithelial Cells/drug effects , Epithelial-Mesenchymal Transition/drug effects , High-Throughput Screening Assays , Phosphoproteins/pharmacology , Protein Kinases/genetics , Animals , Cell Line, Tumor , Epithelial Cells/metabolism , Epithelial Cells/pathology , Epithelial-Mesenchymal Transition/genetics , Female , GTPase-Activating Proteins , Gene Expression Profiling , Gene Expression Regulation , Intercellular Signaling Peptides and Proteins , Mammary Glands, Animal/drug effects , Mammary Glands, Animal/metabolism , Mammary Glands, Animal/pathology , Mice , Protein Kinases/classification , Protein Kinases/metabolism , RNA, Small Interfering/genetics , RNA, Small Interfering/metabolism
4.
J Econ Entomol ; 110(2): 632-640, 2017 Apr 01.
Article in English | MEDLINE | ID: mdl-28334253

ABSTRACT

Sogatella furcifera Horváth (Hemiptera: Delphacidae), is a major migratory pest of rice crops in Asia. The ultrastructure of the flight muscle directly affects the flight ability of insects. The ultrastructure of the flight muscle of some insects can be affected by insecticides. However, the ultrastructure of the flight muscle of S. furcifera and the effect of insecticides on the flight muscle of S. furcifera are not well understood. The present study was conducted to determine the effect of the insecticide dinotefuran on the ultrastructure of the flight muscle of S. furcifera females. In this study, the cross-sectional area and the diameter of the myofibril cross-sections of dinotefuran-treated S. furcifera females increased with the number of days after emergence (DAE), and they were higher than in untreated females. The sarcomere length of myofibrils increased with the number of DAE, and it differed from that of the untreated females. On the first day after emergence, the higher the concentration of dinotefuran, the smaller was the extent of decrease. On the third day after emergence, the higher the concentration of dinotefuran, the larger was the extent of enhancement. For the percentage of mitochondria, those of LC10 and LC20 dinotefuran-treated S. furcifera females increased with the number of DAE and were higher than in untreated females. LC10 dinotefuran-treated S. furcifera females exhibited the largest increase. Thus, our results suggest that the flight ability of S. furcifera increased with time. Some concentrations of dinotefuran can enhance the flight capacity of S. furcifera.


Subject(s)
Flight, Animal/drug effects , Guanidines/pharmacology , Hemiptera/drug effects , Insecticides/pharmacology , Nitro Compounds/pharmacology , Animals , Female , Hemiptera/growth & development , Hemiptera/ultrastructure , Microscopy, Electron, Transmission , Muscle Development/drug effects , Muscles/drug effects , Muscles/ultrastructure , Neonicotinoids , Nymph/drug effects , Nymph/growth & development , Nymph/ultrastructure
5.
J Econ Entomol ; 108(6): 2789-99, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26470376

ABSTRACT

The spatiotemporal distribution of source areas for the early immigration of the white-backed planthopper, Sogatella furcifera (Horvάth), at Xiushan in the middle reach of Yangtze River of China, was analyzed with HYSPLIT (Hybrid Single-Particle Lagrangian Integrated Trajectory) and ArcGIS 10.0. The analysis was based on light trap data collected during April-July in 2000-2012. The synoptic meteorology backgrounds during the immigration periods were analyzed by GrADS (Grid Analysis and Display System). The light trap catches of S. furcifera varied monthly and annually. S. furcifera started immigration in Xiushan in early April to early May, whereas the main immigration period was in July. The distribution of the source areas varied monthly, and the core was moved from the south to the north gradually. The main source areas of S. furcifera in May were in southwestern Guangxi and northern Vietnam. The source areas of S. furcifera in June were located in southwestern Guangxi and western Hunan. Additionally, some of the pests were from southeastern Yunnan. The source areas in July were in northwestern Guangxi, southwestern Guizhou, eastern Yunnan, and the transitional parts of Guangxi, Guizhou, and Yunnan. The sum frequencies of southwest and south winds on the 850 hPa isobaric surface of Xiushan of May-July in heavy occurrence years were more than the light occurrence years. The key meteorological factors were suggested to be vertical perturbation, precipitation, and wind shear during S. furcifera immigration periods.


Subject(s)
Animal Distribution , Hemiptera , Models, Theoretical , Animals , China , Geographic Information Systems , Rivers , Weather
6.
Eur Rev Med Pharmacol Sci ; 18(24): 3844-53, 2014.
Article in English | MEDLINE | ID: mdl-25555875

ABSTRACT

OBJECTIVE: Targeted down-regulation of TGF-ß expression inhibits invasion and metastasis in breast cancer cells. However, the mechanism that TGF-ß functions by remains largely unknown. In the present study we report the mechanism of ERK1/2 dependant S100A4 regulation by TGF-ß and its possible role in TGF-ß-mediated tumour invasion in vitro. MATERIALS AND METHODS: Small interfering RNA targeting TGF-ß1 (TGF-ß1 siRNA) were stably transfected into the breast cancer cell line MDA231. The TGF-ß1 siRNA/9MDA231 cells were then treated with TGF-ß1 (5 ng/ml) or treated with PD98059 (25 µM) or transfected into S100A4 siRNA before TGF-ß1 treatment. The cells were used in several in vitro analyses, including migration, invasion, angiogenesis, and signaling assays. A wound-healing assay was used to determine migration of the cells in culture and a Boyden chamber transwell assay was used for invasion. In vitro angiogenesis studies using conditioned medium in HMEC-1 cells. RESULTS: Inhibition of TGF-ß1 expression by TGF-ß1 siRNA transfection in MDA231 cells showed significant decrease migration, invasion and angiogenesis in vitro. TGF-ß1 siRNA/MDA231 cells treated with 5 ng/ml TGF-ß1 for 24 hs restored the invasive ability of TGF-ß1 siRNA/MDA231 cells. TGF-ß1 treatment could not increase migration, invasion and angiogenesis in TGF-ß1 siRNA/MDA231 cells when treated with 25 µM PD98059 or transfected with S100A4 siRNA before TGF-ß1 treatment. Analysis of TGF-ß1 signaling pathways showed a decrease in p-ERK1/2 activation and an decrease in S100A4 expression. Interestingly, TGF-ß1 regulated S100A4 via ERK1/2 signalling. CONCLUSIONS: Our findings showed that blocking TGF-ß inhibits breast cancer cell invasiveness, migration and angiogenesis via ERK/S100A4 signalling. Therapies targeting the TGF-ß signaling pathway may be more effective to prevent progression in breast cancer.


Subject(s)
Breast Neoplasms/metabolism , Breast Neoplasms/prevention & control , MAP Kinase Signaling System/physiology , Neoplasm Invasiveness/prevention & control , S100 Proteins/biosynthesis , Transforming Growth Factor beta1/antagonists & inhibitors , Cell Line, Tumor , Cell Movement/drug effects , Cell Movement/physiology , Female , Flavonoids/pharmacology , Humans , MAP Kinase Signaling System/drug effects , RNA, Small Interfering/administration & dosage , S100 Calcium-Binding Protein A4 , Signal Transduction/drug effects , Signal Transduction/physiology , Transforming Growth Factor beta1/biosynthesis
7.
Genet Mol Res ; 12(2): 1924-33, 2013 Jun 13.
Article in English | MEDLINE | ID: mdl-23913375

ABSTRACT

Vascular endothelial growth factor (VEGF), the most important regulator of angiogenesis and vascular permeability, is involved in various steps of carcinogenesis. The +936C/T polymorphism of the VEGF gene has been reported to affect the VEGF protein level and to be related to the susceptibility of cancer. However, the results of published studies, as well as the subsequent meta-analyses, remain contradictory. We investigated the association between VEGF +936C/T polymorphism and cancer risk in the Asian population. Twenty-one papers were selected from the PubMed database after a systematic search. Statistics on the frequencies of CC, CT, and TT genotypes of the VEGF +936C/T gene were collected from 8298 cases and 8053 controls. No significant associations between the VEGF +936C/T polymorphism and cancer risk were found for alleles T vs C [odd ratio (OR) = 0.99, 95% confidence interval (95%CI) = 0.93-1.05], TT vs CT/CC (OR = 1.05, 95%CI = 0.88-1.26), CC vs CT/TT (OR = 1.02, 95%CI = 0.96-1.10), and TT vs CC (OR = 1.05, 95%CI = 0.88-1.25). No significant associations were detected in the subgroup analysis by cancer type either. The VEGF +936C/T polymorphism is not associated with risk of overall cancer among Asians.


Subject(s)
Asian People/genetics , Neoplasms/genetics , Polymorphism, Single Nucleotide , Vascular Endothelial Growth Factor A/genetics , Case-Control Studies , Genetic Predisposition to Disease , Humans
8.
Clin Exp Immunol ; 164(1): 57-65, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21361908

ABSTRACT

Human peripheral blood monocytes are a heterogeneous population, including CD14(+) CD16(-) 'classical' monocytes and CD14(+) CD16(+) 'proinflammatory' monocytes. CD16(+) monocytes are expanded in various inflammatory conditions. However, little is known about the CD14(+) CD16(+) monocytes in patients with breast cancer. We detected CD14(+) CD16(+) monocytes in 96 patients with breast cancer and 54 control subjects using flow cytometry. Receiver-operating characteristic (ROC) curve analysis was used to determine the feasibility of CD14(+) CD16(+) monocytes as an indicator for diagnosis of breast cancer. We found that the frequency of CD14(+) CD16(+) monocytes showed a significantly greater increase in breast cancer patients than in controls (16·96% versus 10·84%, P < 0·0001). The area under the ROC curve for CD14(+) CD16(+) monocytes was 0·805 [95% confidence interval (95% CI): 0·714-0·877, P = 0·0001]. Furthermore, the levels of CD16(+) monocytes were significantly negatively associated with the tumour size and pathological staging. In vitro, we showed that CD14(+) CD16(+) monocytes were expanded significantly when the purified CD14(+) monocytes were exposed to Michigan Cancer Foundation (MCF)-7 cells-conditioned medium (MCF-CM) or, separately, to monocyte chemotactic protein 1 (MCP-1). Neutralizing antibodies against MCP-1 inhibited the expansion of CD14(+) CD16(+) monocytes by MCF-CM. Collectively, our findings indicated that MCP-1 can expand CD14(+) CD16(+) monocytes in patients with breast cancer. Furthermore, the CD14(+) CD16(+) monocyte may be a useful indicator in early diagnosis of breast cancer.


Subject(s)
Breast Neoplasms/metabolism , Lipopolysaccharide Receptors/metabolism , Monocytes/metabolism , Receptors, IgG/metabolism , Adult , Aged , Breast Neoplasms/diagnosis , Breast Neoplasms/pathology , Cell Line, Tumor , Cell Proliferation/drug effects , Cells, Cultured , Chemokine CCL2/metabolism , Culture Media, Conditioned/pharmacology , Early Diagnosis , Enzyme-Linked Immunosorbent Assay , Flow Cytometry , GPI-Linked Proteins/metabolism , Humans , Middle Aged , Monocytes/drug effects , Monocytes/pathology
9.
Clin Exp Immunol ; 151(3): 399-406, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18234052

ABSTRACT

Dendritic cells (DCs) can acquire unique features or phenotypes in different tissue microenvironments and decide whether immunity or tolerance develops. DCs observed within the decidua have been implicated in pregnancy maintenance. However, the precise distribution of decidual DC subsets and their phenotypic characteristics are largely unknown. Using flow cytometry, we identified three DC subsets in normal human first-trimester decidua: BDCA-1+ CD19- CD14(-) myeloid DC type 1 (MDC1), BDCA-3+ CD14- myeloid DC type 2 (MDC2) and BDCA-2+ CD123+ plasmacytoid DC (PDC). The percentage of MDC1 to mononuclear cells in the decidua was similar to that in the peripheral blood controls. The percentage of MDC2 in the decidua was significantly higher than that in the peripheral blood controls, whereas the percentage of PDC was significantly lower. Both MDC1 and MDC2 subsets expressed human leucocyte antigen D-related, CD86 and CD80 at low levels, suggesting a characteristic of immature myeloid DCs. Immunoglobulin-like transcript 3, suggested to be involved in immune tolerance induction, was also expressed on decidual MDC1 and MDC2 subsets. In addition, as gestational age increased from 6 to 9 weeks, the numbers of MDC1 decreased but MDC2 increased significantly. This is the first study to demonstrate the presence of three previously unidentified BDCA-1+, BDCA-3+ and BDCA-2+ DC subsets in human decidua, these decidual DCs might play important role in the maintenance of pregnancy.


Subject(s)
Antigens, Surface/metabolism , Decidua/immunology , Dendritic Cells/immunology , Pregnancy/immunology , Antigens, CD1 , Female , Gestational Age , Glycoproteins , Humans , Immune Tolerance/immunology , Immunophenotyping , Lectins, C-Type/metabolism , Membrane Glycoproteins/metabolism , Receptors, Cell Surface/metabolism , Receptors, Immunologic/metabolism , Thrombomodulin
10.
J Chromatogr A ; 1108(1): 14-9, 2006 Mar 03.
Article in English | MEDLINE | ID: mdl-16455091

ABSTRACT

This study proposed a novel headspace gas chromatographic (HS-GC) method for determination of adhesive contaminants (microstickies) in recycled whitewater, a fiber containing process stream, in the paper mill. It is based on the adsorption behavior of toluene (as a tracer) on the hydrophobic surface of microstickies, which affects the apparent vapor-liquid equilibration partitioning of toluene. It was found that the equilibrium concentration of toluene in the vapor phase is inversely proportional to the apparent effective surface area of microstickies that remain in the corresponding solution. Thus, the amount of microsticky materials in the recycled whitewater can be quantified by HS-GC via indirect measurement of the toluene content in the vapor phase of the sample without any pretreatment. The presented method is simple, rapid and automated.


Subject(s)
Adhesives/analysis , Chromatography, Gas/methods , Water Pollutants, Chemical/analysis , Adsorption , Conservation of Natural Resources , Reproducibility of Results , Toluene/chemistry
11.
Breast Cancer Res Treat ; 61(3): 211-6, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10965997

ABSTRACT

Programmed cell death is an important determinant of the response to chemotherapy. Among the factors controlling this process, a significant role is played by bcl-2, bax and p53. The in vitro chemosensitivity of the 177 breast carcinomas was assessed by the histoculture drug response assay (HDRA) using mitomycin C (MMC), 5-fluorouracil (5-Fu), adriamycin (ADM), cisplatin (CDDP), and cyclophosphamide (CPA). The susceptibility of Bcl-2-negative tumors to all the drugs killing was significantly higher than that of Bcl-2-positive tumors. No relationship between Bax or p53 immunoreactivity and sensitivity for any of anticancer drugs studied was demonstrated. Immunohistochemical results regarding Bcl-2 are promising in the evaluation of the sensitivity of cancer cells to a series of anticancer drugs and might be therapeutically useful as an indicator of response to adjuvant chemotherapy for breast cancer.


Subject(s)
Antineoplastic Agents/pharmacology , Breast Neoplasms/metabolism , Carcinoma, Ductal, Breast/metabolism , Carcinoma, Lobular/metabolism , Drug Resistance, Neoplasm , Proto-Oncogene Proteins c-bcl-2/metabolism , Proto-Oncogene Proteins/metabolism , Tumor Suppressor Protein p53/metabolism , Breast Neoplasms/drug therapy , Breast Neoplasms/pathology , Carcinoma, Ductal, Breast/drug therapy , Carcinoma, Ductal, Breast/pathology , Carcinoma, Lobular/drug therapy , Carcinoma, Lobular/pathology , Female , Humans , Immunoblotting , Immunoenzyme Techniques , Statistics, Nonparametric , bcl-2-Associated X Protein
12.
J Hum Genet ; 45(6): 363-6, 2000.
Article in English | MEDLINE | ID: mdl-11185746

ABSTRACT

A growing body of evidence suggests that prostate-specific antigen (PSA) is a novel prognostic factor for breast cancer. The molecular mechanism of variant PSA expression in breast cancer has remained poorly understood in spite of intensive research. Previous studies have shown that the coding region of the PSA gene is not a target for mutations in prostate cancer and breast cancer. The purpose of this study was to analyze genetic variations in the promoter region of the PSA gene, and to detect whether such variations are correlated with PSA mRNA expression in breast tumors. We identified two polymorphisms in the proximal promoter region of the PSA gene. These polymorphisms are located at positions -252 (G or A) and -205 (A or AA), and generate three genotypes. The genotypes were associated with PSA mRNA expression. Our findings suggest that these polymorphisms identified in the proximal promoter region may affect the transcriptional activity of PSA.


Subject(s)
Breast Neoplasms/genetics , Polymorphism, Single-Stranded Conformational , Prostate-Specific Antigen/genetics , Breast Neoplasms/metabolism , Female , Gene Expression , Humans , Prostate-Specific Antigen/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain Reaction
13.
Sheng Li Ke Xue Jin Zhan ; 28(3): 209-13, 1997 Jul.
Article in Chinese | MEDLINE | ID: mdl-11038726

ABSTRACT

Binding of neurotrophins and their receptors lead to dimerization and autophosphorylation of trks. Activated trkA initiates the Ras pathway and finally opens the transcriptions of immediate early genes and delayed response genes or participates directly in physiological responses. Target-derived neurotrophins bind to and induce phosphorylation of trk receptors at the axonal terminal. Active trk or NT-trk or other signal molecules can be retrogradely transported along the axon to transduct messages to neuronal nucleus. There are local autocrine and paracrine mechanisms besides target-derived NTs. Following nervous system injury, increased gene expressions of NTs and their receptors and increased retrograde axonal transport are helpful to survive and regenerate for injured neurons. Lacking NTs and their receptors will result in serious abnormal development of nervous system of mice.


Subject(s)
Nerve Growth Factors/physiology , Receptors, Nerve Growth Factor/physiology , Signal Transduction , Animals , Brain Injuries/metabolism , Humans , Nerve Growth Factors/metabolism , Receptors, Nerve Growth Factor/metabolism
14.
Zhongguo Zhong Xi Yi Jie He Za Zhi ; 14(11): 643-6, 1994 Nov.
Article in Chinese | MEDLINE | ID: mdl-7703628

ABSTRACT

Using spectrum analysis method, the electroencephalogram (EEG) changes of the students who first learned Zhanzhuang Qigong in comparing with the students who did not practice at all were observed, over a period of one year. The results showed that the spectrum of EEG did not change significantly after half year training, but one year later, the alpha index of right frontal and right temporal regions decreased significantly (P < 0.05), and the beta index of right frontal and right temporal regions decreased significantly (P < 0.05). It was indicated that there was a higher tendency of EEG synchyonization, the brain activity changed from "active" to "harmonious" and "calm". It was a gradually adjusting process.


Subject(s)
Brain/physiology , Breathing Exercises , Electroencephalography , Adolescent , Adult , Alpha Rhythm , Beta Rhythm , Cortical Synchronization , Electronic Data Processing , Female , Humans , Male
15.
Zhong Xi Yi Jie He Za Zhi ; 9(8): 488-90, 454, 1989 Aug.
Article in Chinese | MEDLINE | ID: mdl-2598352

ABSTRACT

This study investigated, with microelectrode technic, the effects of electrical activities in pacemaker cells of sinoatrial node by Qixue injection consisting of Ginseng, Astragali and Angelicae sinensis, which may replenish the Qi and invigorate the circulation of blood. Qixue injection produced a negative chronotropic action on beating of sinoatrial node mainly because of lowering the rate of diastolic automatic depolarization and lengthening the duration of diastolic depolarization as well, but this action was caused through neither cholinergic M receptors nor adrenergic beta receptors. With hypoxia at temperature of 41 degrees C or with isoprenaline in existence to cause beating slowness and arrhythmia, Qixue injection turned them into rhythmical beating and quickened automatic beating frequency. It suggested that Qixue injection could antagonize pathologic changes caused by insufficiency of oxygen supply and improve function of sinoatrial node. Also it indicated that Qixue injection had a biphasic function on regulating rhythmical activities of sinoatrial node, which might be one of the mechanisms of the drug used clinically.


Subject(s)
Drugs, Chinese Herbal/pharmacology , Sinoatrial Node/drug effects , Action Potentials/drug effects , Animals , In Vitro Techniques , Microelectrodes , Panax , Plants, Medicinal , Rabbits , Sinoatrial Node/cytology
17.
Pflugers Arch ; 394(1): 78-84, 1982 Jul.
Article in English | MEDLINE | ID: mdl-6289255

ABSTRACT

In small preparations of rabbit sinoatrial node voltage clamp experiments with the two microelectrode technique were carried out. The effects of extracellular barium ions on the slow inward current and outward currents were studied and the following results were obtained: 1. Ba increased the amplitude of the slow inward current without a change in the time course of inactivation. In 10 mM Ba the steady-state inactivation curve (f infinity) shifted in the positive direction (3-4 mV), suggesting a neutralization of negative surface charges. A similar shift of the steady state activation curve (d infinity) could not be detected. 2. Ba reduced the amplitude of the time-dependent (IK, Ix) and time-independent (Ibg) potassium currents in a concentration-dependent manner. 3. The block of the time-dependent potassium current, IK, depended on the membrane potential. The block was stronger at negative than at positive potentials. The block could be relieved by depolarizing pulses, the degree of unblock increased with longer duration of the depolarizing pulse. 4. Ba blocked the slow outward current Ix in a voltage- and time-dependent manner. Like for IK, the block of Ix was stronger at negative than at positive potentials. A given concentration of Ba produced stronger block of Ix than of IK and the removal of block of Ix by depolarizing pulses was slower than the removal of IK block. 5. The effects of Ba on Ix suggest that this current is a potassium current.


Subject(s)
Barium/pharmacology , Ion Channels/drug effects , Potassium/metabolism , Sinoatrial Node/physiology , Action Potentials/drug effects , Animals , Membrane Potentials/drug effects , Rabbits , Time Factors
18.
Pflugers Arch ; 394(1): 85-9, 1982 Jul.
Article in English | MEDLINE | ID: mdl-6289256

ABSTRACT

The elementary conductance of the slow inward current channel in the rabbit sinoatrial node was measured by analysis of the current fluctuations. The preparations were voltage-clamped to -30 mV, where d infinity and f infinity of the slow inward current (Isi) intersect. In the presence of Ba, which increases Isi and decreases outward currents, a small steady-state component of Isi could be detected. The fluctuations of the current in 10 mM Ba were smaller due to the block of the outward channels. They were further reduced after the inhibition of Isi by the Ca channel blocker D600. The spectral power density distribution of the current fluctuations originating from Isi could be fitted at frequencies less than 30 Hz with a single Lorentzian which was attributed to the inactivation process. The corner frequency was 5.28 +/- 1.16 Hz (n = 10), corresponding to an average open time of the single channel of about 30 msec at -30 mV. The single channel conductance was determined to 6.50 +/- 3.15 pS (S.D., n = 10).


Subject(s)
Ion Channels/physiology , Sinoatrial Node/physiology , Animals , Barium/pharmacology , Electric Conductivity , Electricity , Homeostasis , Rabbits
19.
Naunyn Schmiedebergs Arch Pharmacol ; 317(3): 233-7, 1981 Nov.
Article in English | MEDLINE | ID: mdl-6275278

ABSTRACT

The electrophysiological effects of the bradycardic agent AQA 39 (5,6-dimethoxy-2-[3-[[ alpha-(3,4-dimethoxy) phenylethyl] methylamino] propyl] phthalimidine hydrochloride) on small preparations of the S-A node of the rabbit heart were investigated. The following results were obtained: 1. The decrease in the rate of the spontaneous preparation resulted from a lower rate of diastolic depolarization, a slower upstroke and a longer duration of the action potential. Concomitantly, overshoot and maximum diastolic potential were decreased. 2. The drug effect on rate strongly depended on the potential during diastole. AQA 39 acted stronger the more positive the maximum diastolic potential. 3. In voltage-clamp experiments, the membrane potential was held at -40 mV and transiently depolarized by square pulses to -10 mV. At a low pulsing rate (0.005 Hz), the main effect was a reduction of the time-dependent potassium current (Ik); the slow inward current (Isi) was only slightly reduced. However, when the pulsing rate was increased to 1 Hz, a clear reduction of Isi was observed. 4. When the block of Ca channels had reached a steady state during continuous pulsing in the presence of the drug, part of the block could be removed by rest periods, relief of block being dependent on the membrane potential during rest. At a fixed rest period of 45s, relief of block was nearly complete for potentials negative to -55 mV but negligible positive to -35mV. 5. AQA 39 shifted the dose-response curve to ionophoretic application of acetylcholine to higher concentrations, suggesting a competitive action of the drug with acetylcholine at the muscarinic receptor.


Subject(s)
Ion Channels/metabolism , Parasympatholytics/pharmacology , Phthalimides/pharmacology , Sinoatrial Node/physiology , Acetylcholine/pharmacology , Animals , Diastole/drug effects , Electric Stimulation , Electrophysiology , In Vitro Techniques , Ion Channels/drug effects , Isoindoles , Membrane Potentials/drug effects , Potassium/metabolism , Rabbits , Sinoatrial Node/drug effects
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