Development of autonomic dysfunction with intermittent hypoxia in a lean murine model

Area of Science:

• Cardiovascular physiology
• Autonomic nervous system function
• Metabolic regulation

Background:

• Intermittent hypoxia (IH) causes hypertension and alters blood glucose (BG) diurnal variation in lean mice.
• Glucose infusion can attenuate IH-induced hypertension but worsen BG fluctuations.

Purpose of the Study:

• To investigate the impact of IH and glucose infusion on autonomic dysfunction using cardiovascular variability analysis.
• To determine the independent and combined effects of IH and hyperglycemia on autonomic control.

Main Methods:

• Mice were exposed to intermittent hypoxia (IH) or intermittent air (IA) with saline or glucose infusion.
• Cardiovascular variability analysis, including baroreflex sensitivity and spectral analysis, was employed.
• Ultradian rhythmicity was assessed in pulse interval and blood pressure spectra.

Main Results:

• Baroreflex sensitivity decreased in all groups except controls, indicating autonomic dysfunction.
• Low-frequency power of pulse interval spectrum (vagal activity) decreased faster with glucose infusion.
• Low-frequency power of blood pressure spectrum (sympathetic activity) decreased slower with IH.
• Ultradian rhythmicity was suppressed in IH groups.

Conclusions:

• IH increases sympathetic activity, while glucose infusion reduces parasympathetic activity.
• The combination of IH and hyperglycemia leads to progressive autonomic dysfunction.
• These adverse effects on autonomic control occur independently of obesity.