Tohoku J. Exp. Med., 2009, 217(1)

Deoxygenated Hemoglobin/Myoglobin Kinetics of Forearm Muscles from Rest to Exercise in Patients with Chronic Obstructive Pulmonary Disease

TOMOKO KUTSUZAWA,¹ SUMIE SHIOYA,² DAISAKU KURITA² and MUNETAKA HAIDA³

¹School of Health Sciences, Tokai University, Isehara, Japan
²Department of Internal Medicine, School of Medicine, Tokai University, Isehara, Japan
³Department of Basic Sciences and Molecular Medicine, School of Medicine, Tokai University, Isehara, Japan

Exercise capacity is frequently decreased in patients with chronic obstructive pulmonary disease (COPD), and muscle dysfunction is one factor in this reduction. Studies using ³¹-phosphorus magnetic resonance spectroscopy (³¹P-MRS) have shown that phosphocreatine (PCr) and muscle pH (pHi) are significantly decreased in patients with COPD during mild exercise, suggesting the early activation of anaerobic glycolysis in their muscles. Thus, muscle oxygenation states during exercise might differ between patients with COPD and healthy individuals. We simultaneously measured oxygenation state and pHi in the muscles of patients with COPD during the transition from rest to exercise (on-transition) using near infrared spectroscopy (NIRS) and ³¹P-MRS. Sixteen patients with COPD (aged 68.6 ± 7.5 years) and 7 healthy males (controls; aged 63.3 ± 7.5 years) performed dynamic handgrip exercise (lifting a weight by gripping at a rate of 20 grips per min for 3 min). Patients were classified based on pHi data at the completion of exercise as having a normal (≥ 6.9; n = 8) or a low (< 6.9; n = 8) pHi. The deoxygenated hemoglobin/myoglobin (deoxy-Hb/Mb) in NIRS recordings remained constant or slightly decreased initially (time delay), then increased to reach a plateau. We calculated the time delay and the time constant of deoxy-Hb/Mb kinetics during the on-transition. The time delay was shorter in the group with a low pHi than in the controls. These findings might reflect a slower increase in O₂ delivery in patients with a low pHi, which might partly account for altered muscle energy metabolism.

keywords —— near-infrared spectroscopy; on-transition; oxygenation state; muscle pH; chronic obstructive pulmonary disease.

© 2009 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2009, 217, 9-15

Correspondence: Tomoko Kutsuzawa M.D., School of Health Sciences, Tokai University, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan.

e-mail: tkutsu@is.icc.u-tokai.ac.jp