Microvascular remodeling in the carotid body of spontaneously hypertensive rats: A stereological study

The carotid body (CB) serves as the primary peripheral arterial chemoreceptor in mammals and plays a key role in the regulation of blood pressure by sensing changes in arterial blood gas levels and influencing sympathetic nerve activity. It is one of the most highly vascularized organs, with blood vessels occupying approximately 25% of its volume. Although hypertensive conditions are known to induce CB structural plasticity, detailed morphometric analysis of its vasculature remains limited. We performed a quantitative stereological study to assess microvascular remodeling in the CB of spontaneously hypertensive rats (SHR) compared to normotensive Wistar rats (NWR). High-resolution electron microscopy was used to visualize the vascular architecture of the hypertensive CB, and stereological techniques were applied to estimate the total length of its capillary network and the cross-sectional area of one capillary. We found that the total capillary length in the CB of SHR (10.66 ± 0.60 mm) is twice the one in NWR (5.36 ± 0.36 mm). Conversely, the average capillary cross-sectional area was significantly reduced in SHR (20.6 ± 1.14 μm²) versus NWR controls (57.80 ± 1.23 μm²), indicating a denser capillary network in the hypertensive CB. Our findings demonstrate pronounced microvascular remodeling in the hypertensive CB of rats, characterized by an elongated capillary network. Such changes reflect a hypervascular state that may facilitate enhanced chemoreflex sensitivity. This study provides quantitative evidence supporting the role of CB vasculature in hypertensive pathophysiology and highlights its potential as a target for therapeutic modulation.