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  • 1
    Publication Date: 1995-05-19
    Description: Excitation-contraction coupling was studied in mammalian cardiac cells in which the opening probability of L-type calcium (Ca2+) channels was reduced. Confocal microscopy during voltage-clamp depolarization revealed distinct local transients in the concentration of intracellular calcium ions ([Ca2+]i). When voltage was varied, the latency to occurrence and the relative probability of occurrence of local [Ca2+]i transients varied as predicted if Ca2+ release from the sarcoplasmic reticulum (SR) was linked tightly to Ca2+ flux through L-type Ca2+ channels but not to that through the Na-Ca exchanger or to average [Ca2+]i. Voltage had no effect on the amplitude of local [Ca2+]i transients. Thus, the most efficacious "Ca2+ signal" for activating Ca2+ release from the SR may be a transient microdomain of high [Ca2+]i beneath an individual, open L-type Ca2+ channel.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lopez-Lopez, J R -- Shacklock, P S -- Balke, C W -- Wier, W G -- HL02466/HL/NHLBI NIH HHS/ -- HL29473/HL/NHLBI NIH HHS/ -- HL50435/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1995 May 19;268(5213):1042-5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Maryland, School of Medicine, Baltimore 21201, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7754383" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Calcium Channels/drug effects/*physiology ; Electric Stimulation ; Guinea Pigs ; In Vitro Techniques ; Ion Channel Gating/physiology ; Membrane Potentials/physiology ; Microscopy, Confocal ; Myocardium/*metabolism ; Patch-Clamp Techniques ; Probability ; Sarcoplasmic Reticulum/metabolism ; Verapamil/pharmacology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 1994-01-28
    Description: As changes in synaptic strength are thought to be critical for learning and memory, it would be useful to monitor the activity of individual identified synapses on mammalian central neurons. Calcium imaging of cortical neurons grown in primary culture was used to visualize the activation of individual postsynaptic elements by miniature excitatory synaptic currents elicited by spontaneous quantal release. This approach revealed that the probability of spontaneous activity differed among synapses on the same dendrite. Furthermore, synapses that undergo changes in activity induced by glutamate or phorbol ester treatment were identified.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Murphy, T H -- Baraban, J M -- Wier, W G -- Blatter, L A -- New York, N.Y. -- Science. 1994 Jan 28;263(5146):529-32.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7904774" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Cells, Cultured ; Cerebral Cortex ; Dendrites/*metabolism ; Glutamates/pharmacology ; Glutamic Acid ; Kinetics ; Microelectrodes ; Neuronal Plasticity ; Neurons/*physiology ; Phorbol Esters/pharmacology ; Rats ; Receptors, N-Methyl-D-Aspartate/physiology ; Synapses/*physiology ; *Synaptic Transmission ; Tetrodotoxin/pharmacology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 1980-03-07
    Description: Aequorin signals in mammalian heart muscle cells reveal the existence of two temporally distinct processes that increase cytoplasmic calcium ions after membrane excitation. The differential dependence of these processes on the pattern of stimulation suggests that the first process is, or is closely related to, calcium entry through the surface membrane and that the second is calcium release from intracellular storage sites.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wier, W G -- New York, N.Y. -- Science. 1980 Mar 7;207(4435):1085-7.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/7355274" target="_blank"〉PubMed〈/a〉
    Keywords: Action Potentials ; Aequorin/metabolism ; Animals ; Calcium/*metabolism ; Cell Compartmentation ; Dogs ; Heart Conduction System/*metabolism ; In Vitro Techniques ; Ion Channels/metabolism ; Membrane Potentials ; *Myocardial Contraction ; Purkinje Fibers/*metabolism ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 4
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1987-12-18
    Description: Recordings have been made of changes in intracellular calcium ion concentration ([Ca2+]i) that can be attributed to the operation of an electrogenic, voltage-dependent sodium-calcium (Na-Ca) exchanger in mammalian heart cells. Guinea pig ventricular myocytes under voltage clamp were perfused internally with fura-2, a fluorescent Ca2+-indicator, and changes in [Ca2+]i and membrane current that resulted from Na-Ca exchange were identified through the use of various organic channel blockers and impermeant ions. Depolarization of cells elicited slow increases in [Ca2+]i, with the maximum increase depending on internal [Na+], external [Ca2+], and membrane voltage. Repolarization was associated with net Ca2+ efflux and a decline in the inward current that developed instantaneously upon repolarization. The relation between [Ca2+]i and current was linear, and the slope was made steeper by hyperpolarization.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Barcenas-Ruiz, L -- Beuckelmann, D J -- Wier, W G -- HL29473/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1987 Dec 18;238(4834):1720-2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Physiology, University of Maryland School of Medicine, Baltimore.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3686010" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Calcium/*metabolism ; Carrier Proteins/*physiology ; Cell Membrane/physiology ; Guinea Pigs ; Heart/*physiology ; In Vitro Techniques ; Kinetics ; Membrane Potentials ; Sodium-Calcium Exchanger ; Ventricular Function
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 1987-01-16
    Description: Digital imaging of calcium indicator signals (fura-2 fluorescence) from single cardiac cells has revealed different subcellular patterns of cytoplasmic calcium ion concentration ([Ca2+]i) that are associated with different types of cellular appearance and behavior. In any population of enzymatically isolated rat heart cells, there are mechanically quiescent cells in which [Ca2+]i is spatially uniform, constant over time, and relatively low; spontaneously contracting cells, which have an increased [Ca2+]i, but in which the spatial uniformity of [Ca2+]i is interrupted periodically by spontaneous propagating waves of high [Ca2+]i; and cells that are hypercontracted (rounded up) and that have higher levels of [Ca2+]i than the other two types. The observed cellular and subcellular heterogeneity of [Ca2+]i in isolated cells indicates that experiments performed on suspensions of cells should be interpreted with caution. The spontaneous [Ca2+]i fluctuations previously observed without spatial resolution in multicellular preparations may actually be inhomogeneous at the subcellular level.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wier, W G -- Cannell, M B -- Berlin, J R -- Marban, E -- Lederer, W J -- HL25675/HL/NHLBI NIH HHS/ -- HL29473/HL/NHLBI NIH HHS/ -- New York, N.Y. -- Science. 1987 Jan 16;235(4786):325-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/3798114" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Benzofurans ; Calcium/*metabolism ; Cell Compartmentation ; Fura-2 ; In Vitro Techniques ; Myocardial Contraction ; Myocardium/*cytology/metabolism ; Rats ; Spectrometry, Fluorescence ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physiology 52 (1990), S. 467-481 
    ISSN: 0066-4278
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine , Biology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Molecular and cellular biochemistry 89 (1989), S. 97-102 
    ISSN: 1573-4919
    Keywords: calcium ; sodium ; fura-2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Membrane currents and changes in intracellular calcium ion concentration ([Ca2+]i) have been recorded that can be attributed to the operation of an electrogenic, voltage-dependent sodium-calcium (Na-Ca) exchanger in mammalian heart cells. Single guinea-pig ventricular myocytes under voltage clamp were perfused internally with the fluorescent Ca2+-indicator, fura-2, and changes in [Ca2+]i and membrane current that resulted from Na-Ca exchange were isolated through the use of various organic channel blockers (verapamil, TTX), impermeant ions (Cs+, Ni2+), and inhibitors of sarcoplasmic reticulum (ryanodine). The I-V relation of Na-Ca exchange was obtained from the Ni2+-sensitive current elicited by ramp repolarization from +90 mV to −80 mV. Ramps were sufficiently rapid that little change in [Ca2+]i occured during the ramp. The (constant) [Ca2+]i during the ramp was varied over the range 100 nM to 1000 nM by varying the amplitude and duration of a pre-pulse to the ramp. The reversal potential of the Ni2+-sensitive ramp current varied linearly with 1n([Ca2+])i. The I-V relations at different [Ca2+]i over the range −60 mV to +140 mV were in reasonable accord with the predictions of a simple, simultaneous scheme of Na-Ca exchange, on the basis that only [Ca2+]i had changed. The relationship between [Ca2+]i and current at a constant membrane voltage was also in accord with this scheme. We suggest that Ca2+-fluxes through the exchanger during the cardiac action potential can be understood quantitatively by considering the binding of Ca2+ to the exchanger during the [Ca2+]i-transient and the effects of membrane voltage on the exchanger.
    Type of Medium: Electronic Resource
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  • 8
    Publication Date: 1983-12-01
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 9
    Publication Date: 1992-05-15
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 10
    Publication Date: 1990-10-01
    Print ISSN: 0066-4278
    Electronic ISSN: 1545-1585
    Topics: Biology , Medicine
    Published by Annual Reviews
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