Vasodilation of the Cutaneous Microvasculature in Response to Local Heating Post-Stroke

Objective: Peripheral microvascular dysfunction following a stroke is understudied and could negatively impact cardiovascular health and muscle function during recovery. Microvascular reactivity was compared in chronic stroke survivors vs. matched controls by examining microvascular vasodilation to localized gradual and rapid heating, and the neurogenic axonal reflex response. Hypothesis: Stroke survivors have decreased vasodilation in response to local heating compared to matched controls. Methods: Twenty stroke survivors (age 59±14 years, 55% female, 7±6 years post-stroke) and twenty age- and sex-matched controls (age 58±15 years) completed the study. Laser Doppler flowmetry probes with integrated heaters were placed on the paretic and non-paretic anterior thighs of stroke survivors, and on the dominant thigh of controls. Heaters were clamped at 33°C while participants rested for 15 min. The skin was gradually heated to 39°C at 1°C/5 min or rapidly at 0.1°C/s. All heaters were increased to 43°C to determine maximum vasodilatory response. Mean arterial pressure (MAP) was measured every 5 min. Cutaneous vascular conductance (CVC) was calculated as: flux/MAP. Maximum vasodilatory response was calculated as: [(flux/MAP)/(max flux)*100]. Initial rapid rise in skin blood flow during rapid heating at 0.1°C/s, mediated by the neurogenic axonal reflex, was averaged over the 30-second window during the initial peak increase in flux. Data & Results: There was no difference in the microvascular response to gradual heating in the paretic leg (39±16 %CVC max ) compared to the non-paretic leg of stroke survivors (46±17 %CVC max , p=0.07) and the dominant leg of controls (38±20 %CVC max , p=0.82). No difference was observed during rapid heating in the paretic leg (48±17 %CVC max ) compared to the non-paretic (47±16 %CVC max , p=0.91) and control leg (41±14 %CVC max , p=0.08). A similar neurogenic response was observed in the paretic (26±11 %CVC max ) vs. non-paretic leg (26±9 %CVC max , p=1.00) of stroke survivors and vs. the dominant leg of controls (31±13 %CVC max , p=0.22 vs. paretic leg). Conclusions: Peak cutaneous microvascular reactivity to gradual and rapid local heating was similar between the legs of stroke survivors and matched controls. Similar neurogenic responses were observed between stroke survivors and healthy controls. Future studies should evaluate the vasodilatory pathways in response to local heating, as there may be limb-specific changes in vasoactive mediators post-stroke that are not evident by examining the magnitude of vasodilation alone. Microdialysis could be used to study nitric oxide-mediated dilation by infusing L-NAME (L-Nitro-Arginine Methyl Ester), a specific nitric oxide synthase inhibitor, during local heating. This project was supported by the National Institute of Child Health and Human Development at the National Institutes of Health Grant R01HD112258 (to M.J.D. and A.S.H.). 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.