Molecular signaling for pressure-induced constriction in cerebral pericytes from the arteriole-capillary transition zone

Background: Pericytes are a heterogenous population of contractile cells that wrap around capillaries, the smallest blood vessel. Positioned at the key conversion of laminar to single-file red blood cell flow, pericytes in the arteriole-capillary transition (ACT) zone have emerged as potential orchestrators of capillary blood flow. Our preliminary work established that ACT pericytes robustly constrict in response to increased luminal pressure, relying on the Transient Receptor Potential C3 (TRPC3) channel to drive membrane depolarization. However, the upstream processes that trigger pericyte contraction are largely unknown. This study aims to identify the molecular components and their requisite signaling that initiates the pericyte pressure-induced constriction. Hypothesis: We hypothesize that the ACT pericytes utilize the Angiotensin II Type 1 Receptor (AT1R) as a mechanosensitive G-protein Couple Receptor (GPCR) that initiates signaling to engage TRPC3 channels for membrane depolarization and subsequent constriction in response to increased luminal pressure. Methods: We utilized an ex vivo methodology, employing a lab-developed Capillary-Parenchymal Arteriole preparation for pressure myography, confocal fluorescent imaging, and sharp microelectrode electrophysiology. With these approaches, we measured capillary diameter, characterized pericyte Ca 2 + dynamics, and recorded membrane potentials across controlled luminal pressure changes. Pharmacological AT1R inhibition and genetic deletion of TRPC3 channels were used to define their contributions to pressure-induced constriction. Results: ACT pericytes exhibited robust pressure-dependent constriction (60% constriction at 40 mmHg) accompanied by increased intracellular Ca 2 + (mean ΔF/F +2, mean frequency +0.4 event/sec from 20 to 40 mmHg) and membrane depolarization (-28 mV at 40 mmHg). We additionally found that this response is substantially dampened by AT1R inhibition (40% decrease in tone at 40 mmHg). Furthermore, we demonstrated that TRPC3 channels are essential for ACT pericyte-induced contraction, as genetic TRPC3 knockout pericytes exhibited markedly reduced membrane depolarization (-36 mV at 40 mmHg) and a substantial loss of tone generation (10% constriction at 40 mmHg). Remarkedly, smooth muscle cells in attached upstream arterioles from TRPC3 KO mice still showed intact myogenic constriction (40% at 40 mmHg, ns difference from control), suggesting a pericyte specific mechanism. We propose a signaling link between AT1R and TRPC3, as pericyte contraction induced by Angiotensin II AT1R agonism requires functional TRPC3 channels, demonstrated with a 50% constriction in WT pericytes and a ~5% constriction in TRPC3 KO pericytes. Conclusions: Our study reveals that brain ACT pericytes have a distinct molecular response to increased luminal pressure, involving a mechanosensitive AT1R-TRPC3 signaling axis that drives membrane depolarization and pericyte contraction. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.