Na <sub>X</sub> Channel Is a Physiological [Na <sup>+</sup> ] Detector in Oxytocin- and Vasopressin-Releasing Magnocellular Neurosecretory Cells of the Rat Supraoptic Nucleus
Bibliographic record
Abstract
The Scn7A gene encodes Na X , an atypical noninactivating Na + channel, whose expression in sensory circumventricular organs is essential to maintain homeostatic responses for body fluid balance. However, Na X has also been detected in homeostatic effector neurons, such as vasopressin (VP)-releasing magnocellular neurosecretory cells (MNC VP ) that secrete VP (antidiuretic hormone) into the bloodstream in response to hypertonicity and hypernatremia. Yet, the physiological relevance of Na X expression in these effector cells remains unclear. Here, we show that rat MNC VP in males and females is depolarized and excited in proportion with isosmotic increases in [Na + ]. These responses were caused by an inward current resulting from a cell-autonomous increase in Na + conductance. The Na + -evoked current was unaffected by blockers of other Na + -permeable ion channels but was significantly reduced by shRNA-mediated knockdown of Scn7A expression. Furthermore, reducing the density of Na X channels selectively impaired the activation of MNC VP by systemic hypernatremia without affecting their responsiveness to hypertonicity in vivo . These results identify Na X as a physiological Na + sensor, whose expression in MNC VP contributes to the generation of homeostatic responses to hypernatremia. SIGNIFICANCE STATEMENT In this study, we provide the first direct evidence showing that the sodium-sensing channel encoded by the Scn7A gene (Na X ) mediates cell-autonomous sodium detection by MNCs in the low millimolar range and that selectively reducing the expression of these channels in MNCs impairs their activation in response to a physiologically relevant sodium stimulus in vitro and in vivo . These data reveal that Na X operates as a sodium sensor in these cells and that the endogenous sensory properties of osmoregulatory effector neurons contribute to their homeostatic activation in vivo .
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".