Inhibition of L-type Ca<sup>2+</sup>current by C-type natriuretic peptide in bullfrog atrial myocytes: an NPR-C-mediated effect
Bibliographic record
Abstract
Single atrial myocytes were isolated from the bullfrog heart and studied under current and voltage clamp conditions to determine the electrophysiological effects of the C-type natriuretic peptide (CNP). CNP (10(-8) M) significantly shortened the action potential and reduced its peak amplitude after the application of isoproteronol (10(-7) M). In voltage clamp studies, CNP inhibited isoproteronol-stimulated L-type Ca2+ current (ICa) without any significant effect on the inward rectifier K+ current. The effects of cANF (10(-8) M), a selective agonist of the natriuretic peptide C receptor (NPR-C), were very similar to those of CNP. Moreover, HS-142-1, an antagonist of the guanylyl cyclase-linked NPR-A and NPR-B receptors did not alter the inhibitory effect of CNP on ICa. Inclusion of cAMP in the recording pipette to stimulate ICa at a point downstream from adenylyl cyclase increased ICa, but this effect was not inhibited by cANF. These results provide the first demonstration that CNP can inhibit ICa after binding to NPR-C, and suggest that this inhibition involves a decrease in adenylyl cyclase activity, which leads to reduced intracellular levels of cAMP.
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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 | 0.001 | 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".