期刊
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
卷 300, 期 3, 页码 R685-R692出版社
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpregu.00479.2010
关键词
exercise tolerance; deoxygenated hemoglobin; senescence
类别
There are reports of abnormal pulmonary oxygen uptake ((V) over dotO(2)) and deoxygenated hemoglobin ([HHb]) kinetics in individuals with Type 2 diabetes (T2D) below 50 yr of age with disease durations of < 5 yr. We examined the (V) over dotO(2) and muscle [HHb] kinetics in 12 older T2D patients with extended disease durations (age: 65 +/- 5 years; disease duration 9.3 +/- 3.8 years) and 12 healthy age-matched control participants (CON; age: 62 +/- 6 years). Maximal oxygen uptake ((V) over dotO(2max)) was determined via a ramp incremental cycle test and (V) over dotO(2) and [HHb] kinetics were determined during subsequent submaximal step exercise. The (V) over dotO(2max) was significantly reduced (P < 0.05) in individuals with T2D compared with CON (1.98 +/- 0.43 vs. 2.72 +/- 0.40 l/min, respectively) but, surprisingly, (V) over dotO(2) kinetics was not different in T2D compared with CON (phase II time constant: 43 +/- 17 vs. 41 +/- 12 s, respectively). The Delta[HHb]/Delta(V) over dotO(2) was significantly higher in T2D compared with CON (235 +/- 99 vs. 135 +/- 33 AU . l(-1) . min(-1); P < 0.05). Despite a lower (V) over dotO(2max), (V) over dotO(2) kinetics is not different in older T2D compared with healthy age-matched control participants. The elevated Delta[HHb]/(V) over dotO(2) in T2D individuals possibly indicates a compromised muscle blood flow that mandates a greater O-2 extraction during exercise. Longer disease duration may result in adaptations in the O-2 extraction capabilities of individuals with T2D, thereby mitigating the expected age-related slowing of (V) over dotO(2) kinetics.
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