Effects of glucose ingestion on cardiac autonomic nervous system in healthy centenarians: differences with aged subjects

Background Spectral analysis of heart rate variability (HRV) investigates t he cardiac autonomic nervous system (ANS) activity. In particular, low freq uency/high frequency (LF/HF) is considered an index of cardiac sympatho-vag al balance and is stimulated by glucose ingestion in healthy subjects. No s tudies have evaluated the effect of glucose ingestion on cardiac ANS in cen tenarians. Materials and methods In 30 healthy centenarians (HC) and 25 aged subjects (AS) power spectral analysis of HRV was investigated during an oral glucose ingestion. Results Glucose ingestion rose LF/HF ratio in both groups studied. Such sti mulatory effects were restrained to the first 60 min of the study. Independ ent of age, gender, body mass index (BMI) and fasting plasma norepinephrine and FT3 concentrations, HC had basal total power (1318 +/- 546 vs. 1918 +/ - 818 msec(2), P < 0.01), lower low frequency (LF) (33 +/- 21 vs. 50 +/- 11 n.u. , P < 0.03), and higher high frequency (HF) (74 +/- 18 vs. 43 +/- 15 n.u., P < 0.05) than AS. Consequently, LF/HF ratio (0.43 +/- 0.07 vs. 0.91 +/- 0.05, P < 0.02) was also lower in HC than in AS. In AS, but not in HC, the baseline LF/HF ratio correlated significantly with BMI (r = 0.48, P < 0 .01), waist-hip-ratio (WHR) (r = 0.45, P < 0.02), fasting plasma insulin (r = 0.49, P < 0.01) and norepinephrine (r = 0.57, P < 0.02) concentration. G lucose ingestion was associated with a significant rise in LF/HF ratio in b oth groups studied but per cent changes in glucose mediated stimulation of LF/HF was lower in HC than in AS. In a control study, water administration did not affect power spectral parameters of HRV. Conclusion Our study demonstrates that basal- and glucose-stimulated LF/HF, an indirect index of cardiac sympatho-vagal balance, are lower in HC than in AS.