Cholinergic and adrenergic modulation of ionic membrane currents in a rabbit SA node cell model
Bibliographic record
Abstract
We have modified our Hodgkin-Huxley (HH)-type compartmental model of the rabbit sinoatrial node (SAN) cell, to show the effects of cholinergic and adrenergic modulation on certain ionic membrane currents. This study centers on the direct and indirect effects of bath application of acetylcholine (ACh) in the presence or absence of isoprenaline (ISO). Specifically, the direct effect of ACh is on the muscarinic G-protein mediated K/sup +/ current I/sub K,ACh/, while the indirect effect is mediated by the second messenger cyclic adenosine monophosphate (cAMP) which modulates four specific membrane currents: the hyperpolarization-activated inward current (I/sub f/), the long-lasting Ca/sup 2+/ current (I/sub CaL/), the delayed-rectifier K/sup +/ current (I/sub K/) and the Na/sup +/-K/sup +/ pump current (I/sub NaK/). The model also includes material balances on Na/sup +/, Ca/sup 2+/, K/sup +/ and cAMP. The resulting model is capable of mimicking the response of the SAS cell to bath applications of these chemical agents (i.e. inhibitory effects of ACh and the excitatory effects of ISO upon the cycle length). In addition, the model is capable of mimicking the phase sensitivity of the SAN cell in response to both single and periodically-applied ACh stimuli in either the presence and absence of steady background levels of ISO. In these studies, the "ACh stimuli" used represent the local change in ACh concentration produced by the stimulation of a cluster of parasympathetic nerve terminal endings that surround individual pacemaking cells within the SA nodal region of the rabbit heart. Our simulation results for the single cell indicate that the model has a high degree of predictive value in that it can mimic data obtained from multicellular preparations, as well as provide biophysically based explanations for the well known phase-sensitivity of cardiac pacemaker cells to both single and periodically applied ACh stimuli.>
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".