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| Autor | George G. Somjen |
| Titel | Mechanisms of spreading depression and hypoxic spreading depression-like depolarization |
| Zeitschrift | Physiological Reviews |
| Herausgeber | American Physiological Society |
| Ausgabe | 81 |
| Jahr | 2001 |
| Nummer | 3 |
| Seiten | 1065-1096 |
| URL | http://physrev.physiology.org/content/physrev/81/3/1065.full.pdf |
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| Fußnoten | no |
| Fragmente | 3 |
| [1.] Amh/Fragment 005 16 - Diskussion Zuletzt bearbeitet: 2014-05-06 21:40:48 Schumann | Amh, Fragment, Gesichtet, SMWFragment, Schutzlevel sysop, Somjen 2001, Verschleierung |
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| The first paper on SD, titled "Spreading depression of activity in the cerebral cortex" appeared in 1944, written by a young Brazilian investigator, Aristides Leão, working at the Harvard laboratory. Leão wanted to study the electrocorticogram (ECoG) of experimental epilepsy in anesthetized rabbits, but he was distracted from his original goal by an unexpected flattening of the ongoing normal bioelectrical activity that took the place of the anticipated epileptiform field potentials.The silencing of the ECoG trace crept slowly over the cortex, from one recording electrode pair resting on the cortical surface to the one beside it. According to Leão, SD and propagating focal seizures were related phenomena, generated by the same cellular elements, an inference later supported by others. | [page 1066]
The first, seminal paper on SD, titled “Spreading depression of activity in the cerebral cortex” (213) appeared in 1944, written by a young and unknown Brazilian inves- [page 1067] tigator, Aristides Leão, working at the Harvard laboratory of R. S. Morison. Leão wanted to study the cortical electrogram (ECoG) of experimental epilepsy in anesthetized rabbits, but he was distracted from his original goal by an unexpected silencing of the ongoing normal electrical activity that took the place of the anticipated seizure (Fig. 1). The flattening of the ECoG trace crept slowly over the cortex, from one recording electrode pair resting on the cortical surface to the one beside it. According to Leão, SD and propagating focal seizures were related phenomena, generated by the same cellular elements (213), an inference later supported by others (e.g., Ref. 428). 213. LEÃO AAP. Spreading depression of activity in the cerebral cortex. J Neurophysiol 7: 359–390, 1944. 428. VAN HARREVELD A AND STAMM JS. Spreading cortical convulsions and depressions. J Neurophysiol 16: 352–366, 1953. |
No source given, nothing marked as a citation. |
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| [2.] Amh/Fragment 006 05 - Diskussion Zuletzt bearbeitet: 2014-05-07 17:46:23 Hindemith | Amh, Fragment, Gesichtet, SMWFragment, Schutzlevel sysop, Somjen 2001, Verschleierung |
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| The unparalleled increase in extracellular potassium concentration ([K+]o) is accompanied by a precipitous drop in extracellular chloride concentration ([Cl-]o), extracellular sodium concentration ([Na+]o), and extracellular calcium concentration ([Ca2+]o), suggesting that K+ leaving neurons is exchanged against Na+ and Ca2+ that are entering and increased up to 60 mM. [Ca2+]o decreases from its normal level of 1.2-1.5 mM to <0.3 mM. Cations are not exchanged one for one between intra- and extracellular solutions, for the reduction in [Na+]o is greater than the increase in [K+]o. The concomitant drop in [Cl-]o indicates that some of the Na+ entering the cells is accompanied by Cl. It has been suggested that the deficit in extracellular anions is made up by anions leaving the cytosol. Organic anions, including glutamate, have been shown to be released during SD, although some of the glutamate originates from glial cells. | The unparalleled increase in [K+]o (35, 221, 232, 434) is accompanied by a precipitous drop in [Cl-]o, [Na+]o, and [Ca2+]o (78, 124, 128, 187, 281, 283, 373, 448), suggesting that K+ leaving cells is exchanged against Na+ and Ca2+ that are entering (281, 360). [Ca2+]o decreases from its normal level of 1.2-1.5 mM to ,0.3 mM. Cations are not exchanged one for one between intra- and extracellular solutions, for the reduction in [Na+]o is greater than the increase in [K+]o (267). The concomitant drop in [Cl-]o indicates that some of the Na+ entering the cells is accompanied by Cl-. Nicholson (281) suggested that the deficit in extracellular anions is made up by anions leaving the cytosol. Indeed, organic anions, including glutamate, have been shown to be released during SD (71, 81, 395, 397, 420), although some of the glutamate comes from glial cells (170, 171, 394).
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| [3.] Amh/Fragment 007 01 - Diskussion Zuletzt bearbeitet: 2014-05-06 21:07:04 WiseWoman | Amh, Fragment, Gesichtet, SMWFragment, Schutzlevel sysop, Somjen 2001, Verschleierung |
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| [An exact and complete balance sheet of all ingredients displaced during SD is yet to be completed, however, so much larger than that of the interstitial] compartment that neurons need to give up but a fraction of the K+ they contain to achieve a many fold rise in [K+]o. Calculations based on the simultaneously recorded levels of [Na+]o and [K+]o and the known fractional volume of the interstitial space in hippocampal tissue indicate that a much reduced but still substantial trans-membrane potassium concentration gradient remains standing during SD.
The unusual magnitude of the changes in extracellular ion concentrations created the impression that intra- and extracellular ion concentrations equilibrate during SD, and this idea was bolstered by the nearly complete depolarization of neurons during SD. The volume of the cytosol is, however, so much larger than that of the interstitial space that cells need to give up but a fraction of the K+ they contain to achieve a many fold rise in [K+]o. Calculations based on the simultaneously recorded levels of [Na+]o and [K+]o and the known fractional volume of the interstitial space in hippocampus indicate that a much reduced but still substantial transmembrane K+ concentration gradient remains standing during SD. |
An exact and complete balance sheet of all ingredients displaced during SD is yet to be completed, however.
The unusual magnitude of the changes in extracellular ion concentrations created the impression that intra- and extracellular ion concentrations equilibrate during SD, and this idea was bolstered by the nearly complete depolarization of neurons during SD (57, 137, 391; see sect. IIH). The volume of the cytosol is, however, so much larger than that of the interstitial space that cells need to give up but a fraction of the K1 they contain to achieve a manyfold rise in [K+]o. Calculations based on the simultaneously recorded levels of [Na+]o and [K+]o and the known fractional volume of the interstitial space in hippocampus indicate that a much reduced but still substantial transmembrane K+ concentration gradient remains standing during HSD (267) (Figs. 4A and 7D). |
Nothing is marked as a citation. Amh uses the same passage of text twice on the same page. The first time around there are still some slight changes to the original text ("potassium" instead of "K+"). The second time the match is exact |
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