Author(s): OSEI-BOATENG, C., MCCRONE, J.C.1, MINERS, N.I.1, ROY, M.A.2, MAIER, L.E.3, THIESSEN, J.S.1, TSIOROS, S.L.1, PEARY, K.4, STAPLETON, R.K.1, GEERTS, N.3, GABRIELYAN, G.6, FERNANDES, I.A.5, GASHO, C.J.6, SMITH, K.J.4, BAIN, A.R.7, TYMKO, M.M.1, STACEY, B.S.8, Institution: UNIVERSITY OF GUELPH, Country: CANADA, Abstract-ID: 2745

INTRODUCTION:
Neurovascular coupling (NVC) describes the relationship between cerebral blood flow (CBF) and local metabolic demand. Previous research has shown that the NVC response remains either unchanged [1,2] or elevated [3] following high altitude (HA) acclimatization. Whether sex differences exist in NVC following HA acclimatization remains unexplored given the logistical challenge of recruiting a sufficiently powered and matched sample of male and female participants sojourning to terrestrial HA. Considering females have shown higher cerebral blood velocity at sea-level [4], we hypothesized that compared to males, females would also exhibit a greater NVC response at sea-level and throughout HA acclimatization.
METHODS:
Twenty-five healthy participants (12F; 24±3yrs) underwent cardiorespiratory and cerebrovascular monitoring at sea-level (334m) and following early (day 3-4) and late (day 11-12) acclimatization to HA (3,800m). Posterior cerebral artery velocity (PCAv) was measured at rest and during a visual stimulus test (Where’s Waldo) using transcranial Doppler ultrasound. Beat-by-beat arterial blood pressure (finger photoplethysmography) and heart rate (HR; three-lead electrocardiogram in lead II orientation) were continuously recorded.
RESULTS:
At sea-level, baseline PCAv was higher in females compared to males (F: 44.24±11.39 vs. M: 32.69±10.39 cm/s; p=0.019). PCAv increased at HA (p<0.0001) and remained higher in females following acute HA exposure (F: 55±12 vs. M: 44±10 cm/s; p=0.028), however, this difference was eliminated following HA acclimatization (p=0.292). During the NVC test, absolute peak PCAv was higher in females at sea-level (p=0.032). Peak PCAv remained unchanged at HA (p=0.249) but remained higher in females following early HA exposure (p=0.048). This difference was diminished following late HA acclimatization (p=0.328). Absolute mean PCAv response to visual stimulation was higher at HA (p=0.047), but did not differ between sexes (p=0.157).
CONCLUSION:
These data demonstrate that resting PCAv and NVC is higher in females at sea-level and following early (3-4 days) HA acclimatization when compared to males. These differences were, however, abolished following late acclimatization to HA (11-12 days). The physiological implications of these findings warrant further investigation.
1. Caldwell et al. (2017) 2. Stacey et al. (2023) 3. Leacy et al. (2018) 4. Tegeler et al. (2012) 5. Burma et al. (2021)