Effect of tetramethyl pyrazine on L-type calcium channel in rat ventricular myocytes
Bibliographic record
Abstract
To elucidate possible ionic mechanisms of antimyocardial ischemia and antiarrythmia of tetramethyl pyrazine (TP), we studied L-type Ca 2+ currents (I Ca.L ) in adult rat ventricular myocytes using the whole-cell patch-clamp technique. The results showed: (i) under physiological conditions, 0.25 mmol/L TP decreased amplitude of I Ca.L to 60.6% and this inhibition was increased with increasing concentration of TP. ID 50 was 0.20 mmol/L. (ii) The Ca 2+ -antagonistic effect of TP was voltage-dependent. A marked negative shift of the steady-state inactivation curve was observed with long (10 s) conditioning prepulses, but not with short (350 ms) ones. (iii) The time course of inhibition during TP treatment was increased with an increase in drug concentration, and recovery from TP-induced inactivation of I Ca.L was slower than in control cases. (iv) Tonic block and use-dependent block with TP treatment, which was induced by increasing the frequency of stimulation, occurred. We suggest that TP inhibits the I Ca.L mainly by binding to inactivated Ca 2+ channels. The high affinity of TP for the inactivated state of I Ca.L may play an important role in developing therapies for pathological conditions.Key words: Tetramethyl pyrazine, L-type calcium current, rat ventricular myocytes.
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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) | 0.000 | 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) | 0.000 | 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".