ABSTRACT
Blood flow to the active muscles and arterial blood pressure (ABP) increases during dynamic exercise, whereas blood flow to inactive organs (e.g., splanchnic organs and inactive limbs) declines. Aging leads to exaggerated ABP responses to exercise in females, but whether this is related to greater splanchnic vasoconstriction is unknown. This study sought to clarify the effect of aging in females on celiac artery blood flow during dynamic light-intensity exercise. Twelve healthy young females (YF: 20±2yrs, mean±SD) and 12 healthy older females (OF: 71±4yrs) performed dynamic knee-extension and -flexion exercise at 30% of heart rate reserve for 4-min. The absolute changes from baseline (Δ) for mean arterial blood pressure (MAP), celiac artery mean blood flow (celMBF), and celiac vascular conductance (celVC) during exercise were calculated. ABP was measured using an automated sphygmomanometer, and celMBF was recorded by Doppler ultrasonography. The increase in MAP during exercise was greater in OF than in YF (YF: +14±7mmHg, OF: +24±13mmHg, P=0.028). The celMBF decreased during exercise in both groups, but there was no significant difference in the response between YF and OF (YF: -93.0±66.1mL/min, OF: -89.6±64.0mL/min, P=0.951). The celVC also decreased during exercise and remained lower than baseline during exercise. However, the response was not different between YF and OF (YF: -1.8±1.0mL/min/mmHg, OF: -1.5±0.6mL/min/mmHg, P=0.517). These results demonstrate that aging in females has minimal influence on splanchnic artery hemodynamic responses during dynamic light-intensity exercise, suggesting that exaggerated ABP responses during exercise in OF are not due to greater splanchnic vasoconstriction.
ABSTRACT
The purpose of this study was to clarify sex differences in the inhibition of sympathetic vasomotor outflow which is caused by the loading of cardiopulmonary baroreceptors. Ten young males and ten age-matched females participated. The participants underwent a passive leg raising (PLR) test wherein they were positioned supine (baseline, 0º), and their lower limbs were lifted passively at 10º, 20º, 30º, and 40º. Each angle lasted for 3 min. Muscle sympathetic nerve activity (MSNA) was recorded via microneurography of the left radial nerve. Baseline MSNA was lower in females compared to males. MSNA burst frequency was decreased during the PLR in both males (- 6.2 ± 0.4 bursts/min at 40º) and females (- 6.5 ± 0.4 bursts/min at 40º), but no significant difference was detected between the two groups (P = 0.61). These results suggest that sex has minimal influence on the inhibition of sympathetic vasomotor outflow during the loading of cardiopulmonary baroreceptors in young individuals.
