Ultrarapid Delayed Rectifier K<sup>+</sup> Current in H9c2 Rat Ventricular Cell Line: Biophysical Property and Molecular Identity
Bibliographic record
Abstract
Ultrarapid delayed rectifier K(+) currents (I(Kur)s) contribute importantly to cardiac repolarization. However, understanding of I(Kur)s has been hampered by the difficulty of dissecting them from overlapping currents in primary cells. We found with whole-cell patch-clamp recordings that H9c2 cells, a rat ventricular cell line, under 50% confluence (single myoblasts) express exclusively I(Kur)-like current which activates rapidly upon depolarization and partially inactivates during 150-ms pulses. The H9c2 I(Kur) activates within the same voltage range as native cardiac I(Kur)s, with a half-activation voltage of -13 mV. The H9c2 I(Kur) can be completely blocked by tetraethylammonium and 4-aminopyridine. Reversal potential (-79 mV) and envelope-of tail analyses indicate that the H9c2 I(Kur) is carried by a single population of K(+) channels. H9c2 I(Kur) was increased by beta-adrenoceptor-PKA and decreased by alpha(1)-adrenoceptor-PKC activation by isoproterenol and phenylephrine, respectively. Immunocytochemistry was performed with antibodies against 11 different K(+) channels. Positive immuno-stain-ing of the cytoplasmic membrane of H9c2 cells was seen only with Kv3.1b antibody. Antisense oligodeoxynucleotides directed against Kv3.1b subunit sequence significantly inhibited the H9c2 I(Kur). We conclude that the H9c2 cells at the myoblast stage express mainly I(Kur) and Kv3.1b may be a molecular component of the H9c2 I(Kur), and H9c2 cells provide a suitable system for studying I(Kur).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".