Inward Rectifier K+ Currents and Kir2.1 Expression in Renal Afferent and Efferent Arterioles
Bibliographic record
Abstract
The afferent and efferent arterioles regulate the inflow and outflow resistance of the glomerulus, acting in concert to control the glomerular capillary pressure and glomerular filtration rate. The myocytes of these two vessels are remarkably different, especially regarding electromechanical coupling. This study investigated the expression and function of inward rectifier K(+) channels in these two vessels using perfused hydronephrotic rat kidneys and arterioles and myocytes isolated from normal rat kidneys. In afferent arterioles pre-constricted with angiotensin II, elevating [K(+)](0) from 5 to 15 mmol/L induced hyperpolarization (-27 +/- 2 to 41 +/- 3 mV) and vasodilation (6.6 +/- 0.9 to 13.1 +/- 0.6 microm). This manipulation also attenuated angiotensin II-induced Ca(2+) signaling, an effect blocked by 100 micromol/LBa(2+). By contrast, elevating [K(+)](o) did not alter angiotensin II-induced Ca2(+) signaling or vasoconstriction in efferent arterioles, even though a significant hyperpolarization was observed (from -30 +/- 1 to 37 +/- 3 mV, P = 0.003). Both vessels expressed mRNA for Kir2.1 and exhibited anti-Kir2.1 antibody labeling.Patch-clamp measurements revealed prominent inwardly rectifying and Ba(2+)-sensitive currents in afferent and efferent arteriolar myocytes. Our findings indicate that both arterioles express an inward rectifier K(+) current, but that modulation of this current alters responsiveness of only the a different arteriole. The expression of Kir in the efferent arteriole, a resistance vessel whose tone is not affected by membrane potential, is intriguing and may suggest a novel function of this channel in the renal microcirculation.
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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) | 0.001 | 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".