Block of inwardly rectifying K<sup>+</sup>currents by extracellular Mg<sup>2+</sup>and Ba<sup>2+</sup>in bovine pulmonary artery endothelial cells
Bibliographic record
Abstract
Using whole-cell patch clamp technique, we investigated the blocking effects of extracellular Ba2+and Mg2+on the inwardly rectifying K+(KIR) currents of bovine pulmonary artery endothelial cells (BPAEC). The BPAEC KIRchannel has recently been identified as Kir2.1 of the Kir2.0 subfamily. Block of KIRcurrents by Mg2+(3-30 mM) was instantaneous, and increased with hyperpolarization slightly (Kdat -160 and 0 mV was 9.5 and 23.2 mM, respectively). The apparent fractional electrical distance (δ) of the Mg2+binding site is calculated to be 0.07 from the outer mouth of the channel pore. Ba2+(0.3-10 µM) time-dependently blocked the KIRcurrents with a much higher potency and stronger voltage-dependence (Kdat -160 and 0 mV was 1.0 and 41.6 µM, respectively). The Ba2+binding site had a δ value of 0.34. Our data suggest that Mg2+binds to a very superficial site of the KIRchannel, while Ba2+binds to a much deeper site, sensing much more of the membrane electric field. Thus, the BPAEC Kir2.1 appears to be pharmacologically different from the Kir2.1 reported before in bovine aortic endothelial cells (BAEC), which has 2 sites for Mg2+block (a deep site in addition to a shallow one), and a superficial and low-sensitivity site for Ba2+block.Key words: inwardly rectifying K+channel, patch clamp, Ba2+, Mg2+, endothelial cells.
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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 | 0.000 | 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".