Changes of the biophysical properties of calcium-activated potassium channels of rat skeletal muscle fibres during aging
In the present work, we have investigated the effects of the aging process on Ca2+-activated K+ channels (KCa2+) of rat skeletal muscle fibres. KCa2+ channels of adult (5-7 months old) and aged (24-26 months old) rats were surveyed by the patch-clamp technique. In aged rats, KCa2+ channels were routinely detected on the surface membrane of the fibres in both cell-attached and inside-out configurations. Conversely, in adult rat fibres, KCa2+ channels were rarely detected. In the cell-attached configuration, the open probability of the aged rat KCa2+ channel, measured in the range of potentials from -60 mV to +20 mV, was about 1.5-2 times higher than that of the adult one. The number of functional channels was abnormally increased by aging. An average of three channels per patch/area was counted in the inside-out patches of aged rat fibres, whereas no more than one open channel per patch/area was detected in the adult rat fibres. The frequency of finding channels in the patches also increased with aging, i.e. 11.5% and 30.1% in the adult and in the aged rat fibres, respectively. However, no significant change in the single-channel conductance has been observed with aging: it was 227 pS and 231 pS for adult and aged rat channels, respectively. In detached patches, both the adult and aged rat channels showed a similar voltage dependence of open probability and a similar sensitivity to Ca2+ ions. The aging process did not alter the response of the single channel to charybdotoxin, or its modulation by nucleotides, MgATP and adenosine 5'-O-(3-thiotriphosphate) (ATP[gamma-S]). On the other hand, charybdotoxin reduced the abnormally high resting macroscopic K+ conductance of the aged rat fibres, recorded using the two-intracellular-microelectrode technique. These findings indicate that, in skeletal muscle, the activity of KCa2+ channels increases with advancing age.
Medienart: |
Artikel |
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Erscheinungsjahr: |
1997 |
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Erschienen: |
1997 |
Enthalten in: |
Zur Gesamtaufnahme - volume:434 |
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Enthalten in: |
Pflugers Archiv : European journal of physiology - 434(1997), 6 vom: 30. Nov., Seite 822-9 |
Sprache: |
Englisch |
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Beteiligte Personen: |
Tricarico, D [VerfasserIn] |
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Themen: |
115422-61-2 |
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Anmerkungen: |
Date Completed 10.12.1997 Date Revised 21.11.2013 published: Print Citation Status MEDLINE |
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Förderinstitution / Projekttitel: |
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PPN (Katalog-ID): |
NLM09258361X |
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245 | 1 | 0 | |a Changes of the biophysical properties of calcium-activated potassium channels of rat skeletal muscle fibres during aging |
264 | 1 | |c 1997 | |
336 | |a Text |b txt |2 rdacontent | ||
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338 | |a Band |b nc |2 rdacarrier | ||
500 | |a Date Completed 10.12.1997 | ||
500 | |a Date Revised 21.11.2013 | ||
500 | |a published: Print | ||
500 | |a Citation Status MEDLINE | ||
520 | |a In the present work, we have investigated the effects of the aging process on Ca2+-activated K+ channels (KCa2+) of rat skeletal muscle fibres. KCa2+ channels of adult (5-7 months old) and aged (24-26 months old) rats were surveyed by the patch-clamp technique. In aged rats, KCa2+ channels were routinely detected on the surface membrane of the fibres in both cell-attached and inside-out configurations. Conversely, in adult rat fibres, KCa2+ channels were rarely detected. In the cell-attached configuration, the open probability of the aged rat KCa2+ channel, measured in the range of potentials from -60 mV to +20 mV, was about 1.5-2 times higher than that of the adult one. The number of functional channels was abnormally increased by aging. An average of three channels per patch/area was counted in the inside-out patches of aged rat fibres, whereas no more than one open channel per patch/area was detected in the adult rat fibres. The frequency of finding channels in the patches also increased with aging, i.e. 11.5% and 30.1% in the adult and in the aged rat fibres, respectively. However, no significant change in the single-channel conductance has been observed with aging: it was 227 pS and 231 pS for adult and aged rat channels, respectively. In detached patches, both the adult and aged rat channels showed a similar voltage dependence of open probability and a similar sensitivity to Ca2+ ions. The aging process did not alter the response of the single channel to charybdotoxin, or its modulation by nucleotides, MgATP and adenosine 5'-O-(3-thiotriphosphate) (ATP[gamma-S]). On the other hand, charybdotoxin reduced the abnormally high resting macroscopic K+ conductance of the aged rat fibres, recorded using the two-intracellular-microelectrode technique. These findings indicate that, in skeletal muscle, the activity of KCa2+ channels increases with advancing age | ||
650 | 4 | |a Journal Article | |
650 | 4 | |a Research Support, Non-U.S. Gov't | |
650 | 7 | |a Nucleotides |2 NLM | |
650 | 7 | |a Potassium Channels |2 NLM | |
650 | 7 | |a Charybdotoxin |2 NLM | |
650 | 7 | |a 115422-61-2 |2 NLM | |
650 | 7 | |a Calcium |2 NLM | |
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700 | 1 | |a Petruzzi, R |e verfasserin |4 aut | |
700 | 1 | |a Camerino, D C |e verfasserin |4 aut | |
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