Identification of shear stress as a potential regulator of the vasoconduction response along microvascular networks

Vasoconduction can be described by the propagation of vasomotor responses along microvessels. The conducted smooth muscle cell responses along arterioles have been associated with rapid endothelial cell to endothelial cell communication, channel mediated ion flux, and propagated distances up to approximately 2000 µm. The recent discovery of pericyte and ion channel mediated capillary constriction provoke reconsideration of the effects of vasomotion on other vessels within a network, whether constriction of a single capillary can have long range effects, and whether changes in shear stress due to diameter changes might act as a propagation signal. The objective of this study was to computationally estimate the effects of vessel specific vasoconstriction on immediate shear stress changes across a microvascular network. Using images of mesenteric microvascular networks from adult rat tissues immunolabelled for PECAM (endothelial cell marker), a segmental Newtonian flow model was applied, assuming inlet and outlet pressures of 75 mmHg and 10 mmHg, respectively. Representative network regions with an arteriole input vessel and a venule output vessel were selected for analysis. Vessel segments were defined by adjacent nodes. Viscosity was set to 4 cP and assumed to be constant. Shear stresses were estimated per vessel for network scenarios with at least one constricted vessel and compared to the pre-constriction scenario. Constriction was modelled by the extreme case of a vessel diameter be reduced to zero. Based on previous reported value thresholds for effects of shear stress on ion channels, shear stress changes above 1 dyne/cm 2 were used to identify vasoconduction propagation distances. Maximal propagation distances were determined by tracing the vessel path from the segment with shear stress changes greater than 1 dyne/cm 2 to the nearest constricted segment. Vessel ratios represent the numbers of segments that have shear stress changes greater than 1 dyne/cm 2 divided by the numbers of total segments in networks. Vasoconstriction of a single capillary in two network simulation scenarios resulted in maximum propagation distances of 2872 µm and 1718 µm, with affected vessel ratios of 34.8% and 9.6% respectively. Constriction of 5-6 capillaries resulted in maximum propagation distances of 1675 µm and 2010 µm, with affected vessel ratios of 22.9% and 37.9%, respectively. As an additional simulation to evaluate shear stress propagation distances associated with arteriole constriction, an inlet arteriole was reduced by 20%. The propagation distance for the arteriole constriction simulation was 4838 µm; and increased affected vessel ratio to 76.5%. Altogether our results reinvigorate discussion about shear stress as a player in vasoconduction responses and suggest that changes in capillary diameters can influence distal locations within a microvascular network. Funding for this project was supported by the National Science Foundation CBET grant 2309559 and the National Institutes of Health grant R21HL159501. This abstract was presented at the American Physiology Summit 2025 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.