Temporary Sequestration of Potassium by Mitochondria in Astrocytes
Bibliographic record
Abstract
Increases in extracellular potassium concentration ([K(+)](o)), which can occur during neuronal activity and under pathological conditions such as ischemia, lead to a variety of potentially detrimental effects on neuronal function. Although astrocytes are known to contribute to the clearance of excess K(+)(o), the mechanisms are not fully understood. We examined the potential role of mitochondria in sequestering K(+) in astrocytes. Astrocytes were loaded with the fluorescent K(+) indicator PBFI and release of K(+) from mitochondria into the cytoplasm was examined after uncoupling the mitochondrial membrane potential with carbonyl cyanide m-chlorophenylhydrazone (CCCP). Under the experimental conditions employed, transient applications of elevated [K(+)](o) led to increases in K(+) within mitochondria, as assessed by increases in the magnitudes of cytoplasmic [K(+)] ([K(+)](i)) transients evoked by brief exposures to CCCP. When mitochondrial K(+) sequestration was impaired by prolonged application of CCCP, there was a robust increase in [K(+)](i) upon exposure to elevated [K(+)](o). Blockade of plasmalemmal K(+) uptake routes by ouabain, Ba(2+), or a mixture of voltage-activated K(+) channel inhibitors reduced K(+) uptake into mitochondria. Also, reductions in mitochondrial K(+) uptake occurred in the presence of mito-K(ATP) channel inhibitors. Rises in [K(+)](i) evoked by brief applications of CCCP following exposure to high [K(+)](o) were also reduced by gap junction blockers and in astrocytes isolated from connexin43-null mice, suggesting that connexins also play a role in K(+) uptake into astrocyte mitochondria. We conclude that mitochondria play a key role in K(+)(o) handling by astrocytes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".