Selective phenylalkylamine block of <i>I</i><sub>Kr</sub> over other K<sup>+</sup> currents in guinea‐pig ventricular myocytes
Bibliographic record
Abstract
Previous studies on verapamil and D600 have established that the Ca2+‐channel blockers also inhibit delayed‐rectifier K+ currents in cardiac tissues and myocytes. However, estimated IC50 values range over two to three orders of concentration, and it is unclear whether this reflects a high selectivity by one or both of the phenylalkylamines for particular K+ channels. The purpose of the present study was to determine the concentration‐dependent actions of verapamil and D600 on three defined cardiac K+ currents. Guinea‐pig ventricular myocytes in the conventional whole‐cell configuration were bathed with normal Tyrode's or K+‐free solution, and pulsed from −80 mV for measurement of the effects of 0.01 μM to 3 mM verapamil and D600 on the inwardly‐rectifying K+ current (IKl) and the two delayed‐rectifier K+ currents, rapidly‐activating IKr and slowly‐activating IKs. The phenylalkylamines inhibited both inward‐ and outward‐directed IKl. The IC50 values for outward IKl were approximately 220 μM. Verapamil and D600 were approximately equipotent inhibitors of the delayed‐rectifier K+ currents. They inhibited IKr with IC50 near 3 μM, and IKs with IC50 280 μM. These results are discussed in relation to previous findings on K+ currents and to the clinical actions of the drugs. British Journal of Pharmacology (2000) 131, 1809–1816; doi: 10.1038/sj.bjp.0703758
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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 | 0.001 |
| 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".