Mild intermittent hypoxia and metabolism

The present study will investigate the effects of mild intermittent hypoxia (FiO2, 15%) as compared to normoxia (FiO2, 21%) exposure for 7 consecutive days on tissue-specific insulin sensitivity, substrate metabolism, oxygen saturation, adipose tissue and skeletal muscle oxygenation, and substrate metabolism in obese men. Underlying mechanisms will also be studied.

To investigate the effects of moderate IH exposure for 7 consecutive days on wholebody
and tissue-specific insulin sensitivity, substrate metabolism, adipose tissue and
skeletal muscle mitochondrial function/content and PO2 in obese insulin resistant men

During and/or after both normoxia and mild intermittent hypoxia exposure for 7 consecutive days (days 1-7), subjects will undergo the following measurements:

1) Measurement of adipose tissue and skeletal muscle pO2 (two-channel optochemical
measurement system), forearm
blood flow (venous occlusion plethysmography) (day 6).

2) A high-fat mixed-meal test to examine fasting and postprandial metabolite concentrations, substrate metabolism (indirect calorimetry) and systemic inflammatory markers (day 7).

3) A two-step hyperinsulinemic-euglycemic clamp with glucose tracer to measure tissue-specific insulin sensitivity (peripheral, hepatic and adipose tissue insulin sensitivity), and
collection of adipose tissue and skeletal muscle biopsies (day 8).

Obese male subjects will be exposed to 1) mild intermittent hypoxia (FiO2, 15%) and 2) normoxia (FiO2, 21%) for 7 consecutive days (3 cycles of 2h exposure/d in a normobaric room) in a randomized fashion (computer-generated randomization plan; block size, n=4), separated by a 4 week wash-out period.