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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 522 (1988), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 316 (1985), S. 345-347 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Membrane current and voltage recordings were made from enzymatically dispersed single cells isolated from the longitudinal smooth muscle layer of adult rabbit jejunum7. These cells were 5-15 ??? wide, up to 300 ??? long and contracted on application of acetylcholine. Acetylcholine was applied ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 41 (1985), S. 887-894 
    ISSN: 1420-9071
    Keywords: smooth muscle ; K channels ; patch clamp
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Dispersal of the constituent cells of mammalian visceral and vascular smooth muscles has permitted recordings both of membrane currents under whole-cell voltage clamp, and of currents through single ionic channels using the patch-clamp technique. A rectangular depolarizing step applied to a single cell under voltage clamp yielded a net inward current followed by a net outward current in normal physiological solution. In isolated, ‘inside-out’ patches of cell membrane a calcium- and potential-sensitive K channel (100 pS conductance) and a calcium-insensitive, potential-sensitive K+ channel (50 pS conductance) with slow kinetics have so far been identified and characterized.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2013
    Keywords: Smooth muscle ; Ba2+ ; TEA ; Ca2+-activated K+ channels ; Patchclamp ; Channel block
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The interaction of Ba2+ and TEA with Ca2+-activated K+ channels was studied in isolated membrane patches of cells from longitudinal jejunal smooth muscle of rabbit and from guinea-pig small mesenteric artery (100 μm external diameter). Ba2+ applied from the inside of the membrane did not reduce unit current, except at high concentrations, but channels failed to open for long periods (s). This effect became much stronger when the potential gradient was in a direction driving Ba2+ into the channel and was reduced by increasing K+ ion concentration on the outside of the membrane. These results are consistent with Ba2+ entering the open channel and blocking at a site most of the way through the channel bore. In contrast, TEA and procaine dose-dependently reduced unit current amplitude at all patch potentials and slightly increased mean open time. Their effects were not detectably voltage-dependent and could be explained by TEA and procaine blocking the open channel with a timecourse that was faster than the frequency response of the recording system. The lack of appreciable voltage-dependence suggests that TEA and procaine bind to a site near to the inner mouth of the channel.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2013
    Keywords: Smooth Muscle ; Slow Waves ; Carbachol ; Role of Ions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The membrane potential of the cells of the longitudinal muscle of the guinea-pig ileum was recorded intracellularly with glass microelectrodes. Upon changing from isotonic physiological salt solution to sucrose hypertonic solution the spontaneous electrical activity of the membrane was abolished. Spike discharge, but not slow potential changes, was evoked by depolarizing current. In isotonic or in sucrose hypertonic solution, carbachol or acetylcholine caused spike discharge and produced oscillations of the membrane potential (slow waves) which, in hypertonic solution, were about 20 mV in size and 3 sec in duration. The effects on the response to carbachol of varying the ionic composition were examined in sucrose-hypertonic solution. Slow waves in response to carbachol were rapidly and reversibly abolished in sodium-deficient solution, though electrical stimulation evoked spikes for considerable periods. Slow waves were abolished also in sodium-free solution. In contrast, carbachol evoked slow waves after 20 min in calcium-free solution (in which the membrane depolarized) if the membrane was electrically repolarized. In chloride-deficient solution a small but significant (p〈0.05) increase occurred in the duration of slow waves evoked by carbachol. Carbachol elicited slow waves in potassium-free or in potassium-rich solution. The increases in slow wave size and duration in potassium-free solution fell short of statistical significance (0.1〉p〉0.05). The depolarization produced by carbachol was significantly (p〈0.05) less in sodium-deficient (15 mM) solution but was unaffected by alterations in the external chloride concentrations. In sodium-free solution, carbachol hyperpolarized the membrane. The results support a previous suggestion that the slow waves produced by acetylcholine or carbachol represent an inward sodium current through a slow regenerative ion channel.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-2013
    Keywords: Calcium oscillations ; Muscarinic receptor ; Calcium stores ; G protein ; Heparin ; Ryanodine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In single cells isolated from guinea-pig ileal smooth muscle, held under voltage clamp at −40 mV or −50 mV by patch pipette in the whole-cell recording mode, carbachol (CCh) evoked an oscillatory inward cationic current. The frequency of current oscillations increased with increasing CCh concentration. CCh-evoked current oscillations were followed very closely by oscillations in intracellular free Ca2+ estimated from the Indo-1 signal, and were abolished by inclusion of EGTA in the pipette solution. Ryanodine and heparin, but not nifedipine, blocked the generation of current oscillations. CCh-evoked current oscillations were abolished upon withdrawal of extracellular calcium and restored upon its reintroduction. Inclusion of GTP[γS] in the pipette solution caused the generation of an oscillatory inward current, which was blocked by ryanodine. The present results are consistent with the hypothesis that CChevoked cationic current is gated by activation of a G protein and is steeply dependent on [Ca2+]i, fluctuations in the release of Ca2+ from stores during carbachol's action produce oscillations in [Ca2+]i which cause similar oscillations in the cationic current.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-2013
    Keywords: Inositol trisphosphate ; Caged InsP 3 ; Caged ATP ; Heparin ; Calcium current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In single cells obtained by enzymic treatment of rabbit small-intestinal smooth muscle, and held under voltage clamp by patch pipette in the whole-cell recording mode, release of inositol trisphosphate (InsP 3) from its caged precursor by flash photolysis caused complete inhibition of the voltage-dependent calcium current. No inhibition was seen in control experiments where the cage (2-nitrosoacetophenone) was released by flash photolysis from caged ATP. The inhibition by InsP 3 of the calcium current was prevented if 10 mM EGTA or 2 mg/ml heparin was included in the pipette solution. Heparin is known to block InsP 3 receptors. These results suggest that release of calcium stores by InsP 3 raises Cai and that calcium ions inhibit the calcium current by acting either directly or otherwise on the internal mouth of the calcium channel.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-2013
    Keywords: Caffeine ; Methylxanthine ; Smooth muscle ; Calcium channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effect of caffeine on inward current carried by barium ions through voltage-dependent calcium channels has been investigated in single rabbit ear artery cells using whole-cell voltage-clamp techniques. Caffeine (1 –30 mM) caused a rapid and reversible concentration-dependent blockade of barium current and a related compound, 3-isobutyl-1-methylxanthine (IBMX), was a more potent inhibitor of barium current. Caffeine-induced inhibition of barium current showed no voltage- or usedependence and caffeine did not alter the steady-state inactivation of barium current. The effect of caffeine was not blocked by extracellular or by intracellular ryanodine or inclusion of both 5 mM 1,2-bis(2-aminophenoxy)-ethane N,N,N′,N′,-tetraacetic acid (BAPTA) and 2 mM ethylene glycol-bis(β-amino ethyl ether) N,N,N′,N′,-tetraacetic acid (EGTA) in the intracellular solution. Rolipram and M&B 22984, non-xanthine inhibitors of phosphodiesterase, did not diminish inward barium current. The data indicate that caffeine and IBMX block voltage-operated calcium channels and it is suggested that this is due to a direct interaction of methylxanthines with the calcium channel.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-2013
    Keywords: Concentration-jump technique ; Patch-clamp technique ; Single smooth muscle cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A new concentration-jump technique was devised for the rapid application of drugs to single, isolated cells attached to the base of the experimental chamber while recording from them with patch-clamp technique. Cells were placed in a micro-drop (less than 0.1 μl) in a small inner bath which was separated from an outer bath by a ring of “Sylgard” polymer. Stable whole-cell recordings were made in the micro-drop and rapid solution exchange took place when a much larger volume of test solution from the outer bath was flooded over the Sylgard ring and mixed with the micro-drop. Complete equilibration occurred within less than 10 ms.
    Type of Medium: Electronic Resource
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