Diadenosine pentaphosphate increases levels of intracellular calcium in astrocytes by a mechanism involving release from caffeine/ryanodine- and IP3-sensitive stores
Bibliographic record
Abstract
Diadenosine polyphosphates (ApnAs, n = 2 to 6 phosphate groups) activate P2-type cell-surface adenine nucleotide purinoreceptors, increase the influx of calcium into neural cells, and modulate the binding of ryanodine to ryanodine receptor-regulated intracellular calcium release channels. In this study, we tested the hypothesis, using single cell fluorescence techniques and cultured human fetal astrocytes, that p1, P5-di(adenosine-5') pentaphosphate (Ap5A)-induced increases in levels of intracellular calcium ([Ca2+]i) resulted from release of calcium from intracellular pools. Basal [Ca2+]i were 141+/-12 nM and Ap5A increased [Ca2+]i to 980+/-150 nM. The effect of Ap5A on [Ca2+]i was mediated in part through activation of purinoceptors and influx of extracellular calcium because the purinoceptor antagonist pyridoxal-phosphate-6-azophenel-2', 4'-disuphonic acid blocked by 52%, and chelation of extracellular calcium with EGTA prevented, almost completely, Ap5A-induced increases in [Ca2+]i. Implicating calcium release from IP3- and ryanodine-regulated pools of intracellular calcium were findings that Ap5A-induced increases in [Ca2+]i were blocked, at least in part, by thapsigargin, ryanodine, caffeine, and xestospongin, and Ap5A increased by 2-fold the production of IP3. Release of calcium from IP3- and ryanodine-regulated intracellular pools may be an important signaling event in neural cells that are exposed to Ap5A.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".