NIRS Measurement of O2 Dynamics in Contracting Blood and Buffer Perfused Hindlimb Muscle
In order to obtain evidence that Mb releases O2 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 (Δ[deoxy]) was progressively increased at onset of the contraction and reached the plateau under both blood- and buffer-perfused conditions. However, the amplitude of Δ[deoxy] during steady state continued to significantly increase as tension increased. The tension-matched comparison of the Δ[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 PO2 as workload increases.
KeywordsSciatic Nerve Near Infrared Spectroscopy Hindlimb Muscle Peak Tension NIRS Signal
This research was supported by a Grant-in-Aid for Scientific Research from the Japanese Ministry of Education, Science, Sports and Culture (grant #: 18700527, KM), and by the Uehara Memorial Foundation.
- 1.Popel AS. Theory of oxygen transport to tissue. Crit Rev Biomed Engin 1989; 17: 257–321.Google Scholar
- 2.Bank W, Chance B. An oxidative defect in metabolic myopathies: diagnosis by noninvasive tissue oxymetry. Ann Neurol 1995; 27: 512–519.Google Scholar
- 3.Jue T. Measuring tissue oxygenation with the 1H NMR signals of myoglobin. In: RJ Gillies (ed.) NMR in Physiology and Biomedicine, 1994, pp. 199–207. USA: Academic Press.Google Scholar
- 7.Tran TK, Sailasuta N, Kreutzer U, Hurd R, Chung Y, Molé PA, Kuno S, Jue T. Comparative analysis of NMR and NIRS measurements of intracellular PO2 in human skeletal muscle. Am J Physiol 1999; 176: R1682–R1690.Google Scholar
- 14.DeBlasi RA, Ferrari M, Natali A, Conti G, Mega A, Gasparetto A. Noninvasive measurement of forearm blood flow and oxygen consumption by near-infrared spectroscopy. J Appl Physiol 1994; 76: 1388–1393.Google Scholar
- 15.Theorell H. Kristallinisches myoglobin. Biochem Z 1934; 268: 73–82.Google Scholar