| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1Department of Medicine, University of California, San Diego, La Jolla, California; and 2Laboratory of Cardiac Energetics and 3Light Microscopy Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
Submitted 9 August 2004 ; accepted in final form 9 December 2004
The blue autofluorescence (351 nm excitation, 450 nm emission) of single skeletal muscle fibers from Xenopus was characterized to be originating from mitochondrial NAD(P)H on the basis of morphological and functional correlations. This fluorescence signal was used to estimate the oxygen availability to isolated single Xenopus muscle fibers during work level transitions by confocal microscopy. Fibers were stimulated to generate two contractile periods that were only different in the PO2 of the solution perfusing the single fibers (PO2 of 30 or 0–2 Torr; pH = 7.2). During contractions, mean cellular NAD(P)H increased significantly from rest in the low PO2 condition with the core (inner 10%) increasing to a greater extent than the periphery (outer 10%). After the cessation of work, NAD(P)H decreased in a manner consistent with oxygen tensions sufficient to oxidize the surplus NAD(P)H. In contrast, NAD(P)H decreased significantly with work in 30 Torr PO2. However, the rate of NAD(P)H oxidation was slower and significantly increased with the cessation of work in the core of the fiber compared with the peripheral region, consistent with a remaining limitation in oxygen availability. These results suggest that the blue autofluorescence signal in Xenopus skeletal muscle fibers is from mitochondrial NAD(P)H and that the rate of NAD(P)H oxidation within the cell is influenced by extracellular PO2 even at high extracellular PO2 during the contraction cycle. These results also demonstrate that although oxygen availability influences the rate of NAD(P)H oxidation, it does not prevent NAD(P)H from being oxidized through the process of oxidative phosphorylation at the onset of contractions.
oxygen uptake; exercise; oxidative phosphorylation; mitochondria; cellular respiration
This article has been cited by other articles:
|
|
 |
|
  S. T. Kinsey, K. M. Hardy, and B. R. Locke The long and winding road: influences of intracellular metabolite diffusion on cellular organization and metabolism in skeletal muscle J. Exp. Biol., October 15, 2007; 210(20): 3505 - 3512. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Singh, R. J. Mailloux, S. Puiseux-Dao, and V. D. Appanna Oxidative Stress Evokes a Metabolic Adaptation That Favors Increased NADPH Synthesis and Decreased NADH Production in Pseudomonas fluorescens J. Bacteriol., September 15, 2007; 189(18): 6665 - 6675. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. L. Clanton Hypoxia-induced reactive oxygen species formation in skeletal muscle J Appl Physiol, June 1, 2007; 102(6): 2379 - 2388. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. J. van der Laarse, A. L. des Tombe, B. J. van Beek-Harmsen, M. B. E. Lee-de Groot, and R. T. Jaspers Krogh's diffusion coefficient for oxygen in isolated Xenopus skeletal muscle fibers and rat myocardial trabeculae at maximum rates of oxygen consumption J Appl Physiol, December 1, 2005; 99(6): 2173 - 2180. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. T. Kinsey, P. Pathi, K. M. Hardy, A. Jordan, and B. R. Locke Does intracellular metabolite diffusion limit post-contractile recovery in burst locomotor muscle? J. Exp. Biol., July 15, 2005; 208(14): 2641 - 2652. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
