The Experts below are selected from a list of 216 Experts worldwide ranked by ideXlab platform
Tamotsu Takishima - One of the best experts on this subject based on the ideXlab platform.
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Diversity of early afterdepolarizations in guinea pig myocytes: Spatial characteristics of intracellular Ca^2+ concentration
Heart and Vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca^2+ concentration ([Ca^2+]_i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes ( n = 26 from eight hearts) and those with heterogeneous changes ( n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
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Diversity of early afterdepolarizations in guinea pig myocytes: spatial characteristics of intracellular Ca2+ concentration.
Heart and vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca2+ concentration ([Ca2+]i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes (n = 26 from eight hearts) and those with heterogeneous changes (n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
Masahito Miura - One of the best experts on this subject based on the ideXlab platform.
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Diversity of early afterdepolarizations in guinea pig myocytes: Spatial characteristics of intracellular Ca^2+ concentration
Heart and Vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca^2+ concentration ([Ca^2+]_i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes ( n = 26 from eight hearts) and those with heterogeneous changes ( n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
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Diversity of early afterdepolarizations in guinea pig myocytes: spatial characteristics of intracellular Ca2+ concentration.
Heart and vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca2+ concentration ([Ca2+]i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes (n = 26 from eight hearts) and those with heterogeneous changes (n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
W. Melzer - One of the best experts on this subject based on the ideXlab platform.
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Fura-2 calcium signals in skeletal muscle fibres loaded with high concentrations of EGTA.
Cell calcium, 1998Co-Authors: A. Struk, G. Szücs, H. Kemmer, W. MelzerAbstract:Abstract Fura-2 is one of the most frequently used fluorescent Ca indicator dyes; yet it has limitations in tracking large intracellular Ca transients due to its high affinity for Ca. Since high affinity is of advantage when small Ca changes are to be detected, we tried the application of Fura-2 in skeletal muscle fibres which had been loaded with 15 mM internal EGTA to eliminate contractile artifacts. Under these conditions, the free Ca transients are considerably reduced in amplitude and strong saturation of Fura-2 is avoided. Cut segments of isolated muscle fibres were voltage-clamped in a double vaseline gap set-up. In the presence of high internal EGTA, free Ca (as measured with the rapid metallochromic indicator antipyrylazo III) drops rapidly from one value to a lower quasi steady-state value at the end of a depolarizing voltage pulse. This property allowed inspection of the dissociation kinetics of Ca from Fura-2 in the myoplasmic environment. The dissociation rate constant k off in the fibre was determined from the time constant of the exponential decay of the Fura-2 signal as a function of the final level of free Ca. We obtained a value of 26 s −1 at the experimental temperature of 12°C. Knowledge of k off in the cell is essential for reconstructing the time course of free Ca from indicator bound Ca and for estimating the time course of the rate of release from the sarcoplasmic reticulum. The described combination of high EGTA buffering with Fura-2 fluorescence recording may be particularly useful for the determination of Ca release in small muscle cells.
Hirotaka Numaguchi - One of the best experts on this subject based on the ideXlab platform.
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Diversity of early afterdepolarizations in guinea pig myocytes: Spatial characteristics of intracellular Ca^2+ concentration
Heart and Vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca^2+ concentration ([Ca^2+]_i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes ( n = 26 from eight hearts) and those with heterogeneous changes ( n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
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Diversity of early afterdepolarizations in guinea pig myocytes: spatial characteristics of intracellular Ca2+ concentration.
Heart and vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca2+ concentration ([Ca2+]i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes (n = 26 from eight hearts) and those with heterogeneous changes (n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
Nobumasa Ishide - One of the best experts on this subject based on the ideXlab platform.
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Diversity of early afterdepolarizations in guinea pig myocytes: Spatial characteristics of intracellular Ca^2+ concentration
Heart and Vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca^2+ concentration ([Ca^2+]_i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes ( n = 26 from eight hearts) and those with heterogeneous changes ( n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
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Diversity of early afterdepolarizations in guinea pig myocytes: spatial characteristics of intracellular Ca2+ concentration.
Heart and vessels, 1995Co-Authors: Masahito Miura, Nobumasa Ishide, Hirotaka Numaguchi, Tamotsu TakishimaAbstract:We classified early afterdepolarizations (EADs) into subgroups according to the spatial features of the intracellular Ca2+ concentration ([Ca2+]i). Myocytes were enzymatically isolated from guinea pig ventricles. When Fura-2 salt was applied through a whole cell patch pipette after the formation of a gigaohm seal, the membrane potential was measured using the current, clamp technique. When myocytes were loaded with Fura-2 AM, the membrane potential was recorded with a conventional microelectrode technique. Spatio-temporal changes in Fura-2 fluorescence and cell length were recorded simultaneously, using a digital TV system. EADs were induced after superfusion with potassium-free Tyrode solution. Irrespective of the Fura-2 loading procedure, EADs could be classified into those with spatially synchronous fluorescence changes (n = 26 from eight hearts) and those with heterogeneous changes (n = 20 from three hearts). EADs with synchronous features took off from a higher membrane potential (≥−34mV) than EADs with heterogeneous features (≤−57 mV). These results suggest that EADs have at least two constituents.
