The Effects of Acute Hyperglycemia on Cardiac Autonomic Balance Between Sexes

Abstract

Males and females have differential cardiac autonomic functioning, possibly contributing to high rates of cardiovascular disease in men with aging. In addition, there is still a general lack of understanding regarding normal physiology and disease risk in women. In young, healthy populations, a sex difference in cardiovascular autonomic function has not been established. Acute glucose ingestion has been shown to stimulate a cardiovascular sympathetic response, likely through carotid body activation. We hypothesized that young men would have a greater cardiovascular sympathetic response following glucose loading than women, measured through heart rate variability (HRV) metrics. We aimed to test the effects of acute relative hyperglycemia on HRV metrics to study cardiovascular autonomic function between young, healthy men and women. We recruited 40 healthy participants (21.6±1.7 yrs; BMI 24.1±4.2 kg/m2; 19 females), and instrumented them with electrocardiogram (ECG) to measure heart rate (HR) and finger photoplethysmography to measure mean arterial pressure (MAP). Blood glucose was tested using a glucometer and capillary draw via sterile lancets. Cardiovascular measures were recorded at rest in a fasted state and 30‐min after an acute relative hyperglycemic load (75g glucose, 300ml; 4.8±0.4 vs. 7.5±1.3 mmol/L; P<0.0001). HRV was quantified in two ways: frequency domain, with low frequency (LF; sympathetic activity), and high frequency (HF; parasympathetic activity), and with Poincaré plots, deriving SD1 (parasympathetic activity) and SD2 (sympathetic activity). Frequency domain metrics were minimally affected by glucose loading, increasing HF (P=0.03) and decreasing LF (P=0.02). In both fasted and glucose loaded states, LF and HF domains were different between males and females, with males having increased LF values (P<0.001) and females having increased HF domain (P<0.001). SD1 was also significantly increased in females in both fasted and glucose loaded sates (P=0.013). Our data demonstrates a sex difference in cardiovascular autonomic functioning using HRV metrics. Specifically, we observed increased resting sympathetic activity in males, possibly contributing to high rates of cardiovascular disease later in life. Females had increased resting parasympathetic activity, possibly offering clinical relevance in understanding reduced cardiovascular disease risk in women over the lifespan.Support or Funding InformationNSERC Discovery and MRU Faculty of Science and TechnologyThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.