Presenter: Cameron O’Connell – Human Physiology
Faculty Mentor(s): Chris Chapman
Session: (In-Person) Poster Presentation
Sweating during passive heat stress can induce a state of low body water known as hypohydration. Mild hypohydration combined with elevated core body temperature attenuates increases in renal vasoconstriction during a sympathetic stimulus. It is unknown whether hypohydration, independent of heat stress, elicits a similar altered renal hemodynamic response. We tested the hypothesis that prolonged mild hypohydration attenuates reductions in renal artery blood velocity (RBV) during exercise pressor reflex activation compared to a hydrated state (i.e., euhydrated). Eight healthy adults (5 females) performed two trials following 24 hours of fluid deprivation (HYPO) or when euhydrated (EUHY). RBV was assessed using Doppler ultrasonography during two minutes of static handgrip exercise (Handgrip) that was immediately followed by two minutes of post-exercise arterial occlusion (Occlusion). The 24-hour protocol induced a mild hypohydration in HYPO, as noted by greater reductions in body mass (HYPO: -2.2±0.5%; EUHY: -0.3±0.7%, P=0.001). At the end of Handgrip, there was a trend toward attenuated reductions in RBV in HYPO compared to EUHY (HYPO: -1.6±4.8 cm·s-1; EUHY: -6.2±6.0 cm·s-1, P=0.16). At the end of Occlusion, RBV, was not different between conditions (P=0.52). These preliminary findings suggest that prolonged mild hypohydration may attenuate the renal hemodynamic response to the static handgrip phase of exercise pressor reflex activation.