Microvascular rarefaction in the sinoatrial node

This study tested the hypothesis that sinoatrial node microvascular rarefaction occurs in a model of heart failure with preserved ejection fraction (HFpEF). While it has been established that the sinoatrial node exhibits vascular heterogeneity, it was not known whether microvessel density changes regionally or is altered overall during HFpEF. Data provided here demonstrates vascular and pacemaker cell densities under normal conditions with representations at low and high magnifications. 
, Whole-Mount Immunohistochemistry
Following confirmation of isoflurane anesthesia, we rapidly excised hearts and placed them in prewarmed (37 °C) heparinized (0.2 mg/mL) Tyrode III solution (in mM: 140 NaCl, 5.4 KCl, 1.0 MgCl₂, 1.8 CaCl₂, 5.0 HEPES, and 10 d-glucose, pH adjusted to 7.4 with NaOH). We then dissected the SAN and surrounding regions, including portions of the right atrial appendage, superior vena cava, and inferior vena cava. We pinned and stretched the tissues in a 35 mm Sylgard-coated dish, rapidly rinsed them three times in phosphate-buffered saline (PBS), and fixed them in 2 mL of 4% paraformaldehyde (0.01 M PBS) for 1 hour at room temperature. After fixation, we washed the tissues three times with PBS and transferred them to a 50 mL tube containing PBS for 12 hours at 4°C. We performed tissue dehydration, bleaching, and clearing in dimethyl sulfoxide (DMSO) to reduce tissue autofluorescence, as previously described [PMID: 25262932, 16806289]. Briefly, we dehydrated tis..., # Data from: Microvascular rarefaction in the sinoatrial node

Dataset DOI: [10.5061/dryad.k98sf7mmp](https://doi.org/10.5061/dryad.k98sf7mmp)

## Description of the data and file structure

This dataset contains immunofluorescent images of the cardiac sinoatrial node labeled with antibodies against HCN4 and CD31. HCN4 labels cardiac pacemaker cells, and CD31 labels endothelial cells. Images were taken at 10X, 20X, and 60X. For images taken at 10X, the entire cardiac sinoatrial node is visualized along with surrounding tissue, including the right atrial appendage, superior vena cava, and inferior vena cava. Multiple images are taken and stitched together. For the 20X image, just the region encompassing the cardiac sinoatrial node is acquired, where multiple tiled images are stitched together. For the 60X images, single areas of the superior (sSAN) or inferior (iSAN) sinoatrial nodes were acquired.

### Files and variables

#### File: 20241210-HCN4-CD31-10X-Tile.tif

**Description:** Car...,