title: NIRS measurement of O(2) dynamics in contracting blood and buffer perfused hindlimb muscle.
abstract: In order to obtain evidence that Mb releases O(2) during muscle contraction, we have set up a buffer-perfused hindlimb rat model and applied NIRS to detect the dynamics of tissue deoxygenation during contraction. The NIRS signal was monitored on hindlimb muscle during twitch contractions at 1 Hz, evoked via electrostimulator at different submaximal levels. The hindlimb perfusion was carried out by perfusion of Krebs Bicarbonate buffer. The NIRS still detected a strong signal even under Hb-free contractions. The deoxygenation signal (Delta[deoxy]) was progressively increased at onset of the contraction and reached the plateau under both blood- and buffer-perfused conditions. However, the amplitude of Delta[deoxy] during steady state continued to significantly increase as tension increased. The tension-matched comparison of the Delta[deoxy] level under buffer-perfused and blood perfused conditions indicate that Mb can contribute approximately 50% to the NIRS signal. These results clarify the Mb contribution to the NIRS signal and show a falling intracellular PO(2) as workload increases.
authors.affiliation: Kanazawa University, Kanazawa 920-1192, Japan. masuda@ed.kanazawa-u.ac.jp
authors.forename: Kazumi
authors.initials: K
authors.lastname: Masuda
authors.forename: Hisashi
authors.initials: H
authors.lastname: Takakura
authors.forename: Yasuro
authors.initials: Y
authors.lastname: Furuichi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iwase
authors.forename: Thomas
authors.initials: T
authors.lastname: Jue
mesh_terms: D000818:Animals; D002021:Buffers; D006454:Hemoglobins / Q000378:metabolism; D006614:Hindlimb / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D009132:Muscles / Q000502:physiology*; D009211:Myoglobin / Q000378:metabolism; D010100:Oxygen / Q000097:blood*; D010477:Perfusion / Q000379:methods*; D051381:Rats; D017208:Rats, Wistar; D019265:Spectroscopy, Near-Infrared / Q000379:methods*
chemical_list: D002021:Buffers; D006454:Hemoglobins; D009211:Myoglobin; D010100:Oxygen