Vagal blood volume receptors compensate for haemorrhage and posture change

Fig. 1. PIEZO2 mediates a vagal reflex to posture change. a, Representative traces of blood pressure (mean carotid) and heart rate while mice are rotated through different postures on a tilt table. bpm, beats per minute. b, The initial and recovered changes in blood pressure after tilt to the indicated position. Initial change, maximal deviation within first 5 s; recovery BP, the average blood pressure from 1 min after tilt to 1 min and 5 s after tilt; baseline, the average blood pressure for the 5 s before tilt. The individual circles show the average response of one mouse over at least three trials. n = 7 mice. c, Cartoons depicting the anatomy of the vestibular system and vagus nerve. ADN, aortic depressor nerve; CSN, carotid sinus nerve. d, Representative traces of blood pressure (mean carotid) while mice are rotated through different postures on the tilt table. e, Representative blood pressure responses (average across at least three tilts) during upright tilt in the indicated mice. Baroreceptors cut, transection of the glossopharyngeal nerve and SLN. The control mice are littermates lacking Phox2b-cre. f, Quantification of blood pressure recovery after upright rotation. BP recovery…

Fig. 2. Anatomy of vagal sensory neurons in the heart. a, Representative whole-mount images of tdTomato immunofluorescence in the heart (left, dorsal view; right, ventral view) of a Vglut2-ires-cre mouse injected with AAV-flex-tdTomato in the vagal ganglia. Scale bar, 1 mm. LA, left atrium; RA, right atrium. b, Representative confocal images (maximum-intensity projection, two replicates) of a heart from a showing flower-spray terminals (top) and end-net endings (bottom). Scale bars, 200 μm. c, Uniform manifold approximation and projection (UMAP) plots depicting expression (natural log scale) of Piezo2 (top) and Npy2r (bottom) across a previously published vagal/glossopharyngeal cell atlas16. d, Representative confocal images (maximum-intensity projection) of a heart from a Piezo2-ires-cre mouse (top, from eight replicates) or Npy2r-ires-cre mouse (bottom, from six replicates) injected with AAV-flex-tdTomato (magenta) and a Cre-independent AAV-eGFP (green) in the vagal ganglia. Scale bars, 200 μm. e, Quantification of the relative distribution of terminal types observed in each Cre line. Data are mean ± s.e.m. n = 6 (NPY2R) and 9 (PIEZO2) mice. Each dot represents cumulative data from one…

Fig. 3. Vagal mechanosensors fire during atrial and ventricular systole and report on blood volume. a, Cartoon of electrophysiological recordings of the thoracic vagus nerve trunk. Heart diagram created in BioRender. Liu, Z. (2025) https://BioRender.com/a34i357. Scissors diagram created in BioRender. Liu, Z. (2025) https://BioRender.com/s08uo8h. b, Representative, simultaneously recorded electrocardiograms (ECG) and vagal activity from WT (top) and vagal-ΔPiezo2 (bottom) mice at the baseline (left, raw activity) and after intravenous injection (black arrow) of serotonin (right, integrated activity over a 5 s window). c, Representative spike raster of vagal activity (the black dashes show action potentials) across 159 cardiac cycles in a WT mouse. d, The average physiological measurements over 30 s (around 250 cardiac cycles) in four WT mice. RAP, right atrial pressure; LVP, left ventricular pressure; LVV, left ventricular volume. e, Representative spike histograms of average vagal activity patterns (30 s). f, Quantification of phase I (left) and phase II (right) responses from e. Data are mean ± s.e.m. The individual circles show the average response of one mouse over at least 100…

Fig. 4. Different PIEZO2 neurons detect changes in blood and airway volume. a, Cartoon depicting vagal ganglia imaging (left) and a two-photon image (right) of SALSA fluorescence in a representative vagal ganglion (of six replicates) from Vglut2-cre;lsl-SALSA mice. Scale bar, 50 µm. Heart image created in BioRender. Liu, Z. (2025) https://BioRender.com/a34i357. Microscope objective image created in BioRender. Liu, Z. (2025) https://BioRender.com/quy3reu. b, Heat map (left) and the distribution (right) of calcium responses from vagal neurons from Vglut2-cre;lsl-SALSA mice (ΔF/F colour coded, 1,382 imaged neurons, 6 mice) to blood volume infusion (red), airway stretch (black) or both (purple). In total, 140 responsive and some randomly selected non-responsive (grey) neurons are shown. c, Representative calcium activity traces from individual vagal neurons (right) responding to changes in blood volume (B, red) or airway stretch (A, black), and a representative field of view (left) showing the average GCaMP6f fluorescence intensity during peak stimulus application. Scale bars, 20 µm. Representatives were chosen from 1,382 neurons, 6 mice. d, The neuronal responses in PIEZO2+ and PIEZO2−…

Fig. 5. Physiological compensation for blood loss requires PIEZO2. a, Analysis of heart rate (HR) and blood pressure (BP) over time after tail transection in the indicated genotypes. Data are mean (dark lines) ± s.e.m. (shading). n = 17 (Vagal-ΔPiezo2) and 19 (control, Cre-negative littermates) mice (top), and n = 5 (Vagal-ΔPiezo2) and 6 (control, age- and sex-matched WT) mice. Mouse diagram created in BioRender. Liu, Z. (2025) https://BioRender.com/89tllig. b, The average heart rate and blood pressure change between minutes 25 and 35 after haemorrhage onset from the mice in a. Data are mean ± s.e.m. Statistical analysis was performed using two-sided Mann–Whitney U-tests; **P = 0.0043, ****P < 0.0001. c, The survival rate over time of mice after tail-transection-induced haemorrhage. n = 19 (control, including 14 Cre-negative littermates and 5 age- and sex-matched WT) and 20 (Vagal-ΔPIEZO2) mice. Statistical analysis was performed using the log-rank (Mantel–Cox) test; *P = 0.0173. Source Data

Extended Data Fig. 1. Physiological measurements during the tilt table test. a, Blood pressure (top) and heart rate (bottom) traces upon rotation to upright posture in individual mice (grey) or all mice averaged (black), for individual mice, responses are averaged over at least 3 trials, n = 7 mice. b, Representative carotid and femoral blood pressure traces (top) and associated quantification (bottom) upon rotation to upright posture, initial: maximal deviation within first 5 sec, recovered: 2 sec baseline after 1 min, individual circles: average response of one mouse over at least 3 trials, n = 7 mice. c, Measurements in mice of genotypes indicated of baseline blood pressure (BP) in the supine position and the ratio of largest increase in HR to the largest drop in BP within the first 5 s after rotation to an upright posture. Controls include littermates lacking Phox2b-Cre (top left) or heterozygotes containing one Tmie or Otop1 knockout allele, mean ± sem, n = 11 Vagal-ΔPiezo1/2 mice and 9 Cre-negative littermate controls, 6 Vagal-ΔPiezo2 mice and 5 Cre-negative littermate controls, 8 Tmie knockout mice and 8 heterozygote littermate controls, 4 Otop1 knockout mice and 4 heterozygote littermate…

Extended Data Fig. 2. Expression driven by Phox2b-Cre. Representative wholemount images of tdTomato (Phox2b, magenta) and PGP9.5 (green) immunofluorescence in cleared tissues indicated, scale bar: 100 µm except 1 mm for heart, 3 replicates. We note that tdTomato signal in the heart is from extrinsic fibres not intrinsic heart cells.

Extended Data Fig. 3. Normal dose-dependent baroreflex in mice lacking only PIEZO2. a, Representative blood pressure and heart rate traces from control (loxP-Piezo2 lacking a Cre allele) and Vagal-ΔPiezo2 mice in response to intravenous infusion of various doses of PBS or phenylephrine (PE). b, Quantitative analysis of baroreflex sensitivity across mice reveals a similar slope (ΔHR/ΔBP) of -7.1 in control mice and -8.9 in Vagal-ΔPiezo2 mice, Control: black dots, 30 trials from 5 mice, Vagal-ΔPiezo2: red dots, 24 trials from 4 mice, lines fitted by linear regression, ns: p > 0.05 between slopes by an analysis of covariance (ANCOVA) test. Source Data

Extended Data Fig. 4. Symmetry of vagal sensory axons in the cardiovascular system. a, Cartoon of two-colour anatomical tracing of vagal sensory neurons in the heart, heart and syringe images created in BioRender. Lu, S. (2025) https://BioRender.com/ebmngtc. The left and right vagal ganglia of Vglut2-ires-Cre mice were injected with AAV-flex-tdTomato and AAV-flex-eGFP respectively and later, two-colour wholemount immunostaining was performed on the heart. Representative low magnification (b, c, scale bar: 1 mm) and high magnification (d, scale bar: 200 µm) confocal images (maximum intensity projection) of ventricle tissue sections, intact aorta or intact atria, 4 replicates.

Extended Data Fig. 5. Regionalization of vagal sensory axons in the atrium. Representative confocal image of tdTomato immunofluorescence (5 replicates) near the atrium-vena cava junction of Piezo2-ires-Cre (a, left) and Npy2r-ires-Cre (b, right) mice previously injected in vagal ganglia with AAV-flex-tdTomato, scale bars: 1 mm, heart image created in BioRender. Lu, S. (2025) https://BioRender.com/h0xd2qa.

Extended Data Fig. 6. Normal hemodynamic responses on the tilt table require PIEZO2 neurons. Representative traces of mean carotid blood pressure while mice are rotated from supine to upright (1), upright to prone (2), prone to upright (3) and upright to supine (4). Piezo2-ires-Cre; lsl-DTR and Npy2r-ires-Cre; lsl-DTR mice were injected in vagal ganglia with DT (VagalABLATE) or PBS (Control), and were selected from mice used in Fig. 2f.

Extended Data Fig. 7. Subtypes of PIEZO2-positive vagal sensory neurons that are dispensable for heartbeat-coupled responses. a, UMAP plots depicting expression (natural log scale) of Phox2b, Piezo2, P2ry1, Glp1r, Pvalb and Oxtr based on a previously published vagal/glossopharyngeal cell atlas16. b, DTR immunostaining of vagal ganglia from P2ry1-ires-Cre; loxP-DTR, Pvalb-ires-Cre; loxP-DTR, Oxtr-ires-Cre; loxP-DTR and Glp1r-ires-Cre mice (left to right: 10, 7, 7, 6 replicates) that received no injection (top) or unilateral DT injection (bottom), scale bars: 500 µm. c, Representative (from replicates above) and simultaneously recorded electrocardiograms (ECG) and vagal nerve activity traces from the vagus nerve trunk corresponding to DT-injected ganglia of mice in b. d, Quantification of heartbeat-coupled vagal nerve trunk activity and intravenous saline infusion-induced vagal nerve trunk activity, mean ± sem, n = 12, 10, 7, 7, 6 mice, WT mice are the same reported in 3f and 3h. No statistical significance observed (p > .05) or **p = .0098 by a one-way ANOVA compared to wild-type (WT) with a Bonferroni correction for multiple comparisons. Source Data