| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Medicine, Physiology Division, University of California, San Diego, La Jolla, California 92093-0623
The purpose of this investigation was to study the effects of altered extracellular PO2 (PEO2) on the intracellular PO2 (PIO2) response to contractions in single skeletal muscle cells. Single myocytes (n = 12) were dissected from lumbrical muscles of adult female Xenopus laevis and injected with 0.5 mM Pd-meso-tetra(4-carboxyphenyl)porphine for assessment of PIO2 via phosphorescence quenching. At a PEO2 of ~20 (low), ~40 (moderate), and ~60 (high) Torr, tetanic contractions were induced at a frequency of 0.67 Hz for ~2 min with a 5-min recovery between bouts (blocked order design). The PIO2 response to contractions was characterized by a time delay followed by a monoexponential decline to steady-state (SS) values. The fall in PIO2 to SS values was significantly greater at each progressively greater PEO2 (all P < 0.05). The mean response time (time delay + time constant) was significantly faster in the low (35.2 ± 5.1 s; P < 0.05 vs. high) and moderate (43.3 ± 6.4 s; P < 0.05 vs. high) compared with high PEO2 (61.8 ± 9.4 s) and was correlated positively (r = 0.965) with the net fall in PIO2. However, the initial rate of change of PIO2 (calculated as net fall in PIO2/time constant) was not different (P > 0.05) among PEO2 trials. These latter data suggest that, over the range of 20-60 Torr, PEO2 does not play a deterministic role in setting the initial metabolic response to contractions in isolated frog myocytes. Additionally, these results suggest that oxidative phosphorylation in these myoglobin-free myocytes may be compromised by PEO2 at values nearing 60 Torr.
Xenopus laevis; oxidative phosphorylation; myoglobin
This article has been cited by other articles:
|
|
 |
|
  A. M. Jones, D. P. Wilkerson, and J. Fulford Muscle [phosphocreatine] dynamics following the onset of exercise in humans: the influence of baseline work-rate J. Physiol., February 1, 2008; 586(3): 889 - 898. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. A. Howlett, C. A. Kindig, and M. C. Hogan Intracellular PO2 kinetics at different contraction frequencies in Xenopus single skeletal muscle fibers J Appl Physiol, April 1, 2007; 102(4): 1456 - 1461. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Burnley, C. L. Roberts, R. Thatcher, J. H. Doust, and A. M. Jones Influence of blood donation on O2 uptake on-kinetics, peak O2 uptake and time to exhaustion during severe-intensity cycle exercise in humans Exp Physiol, May 1, 2006; 91(3): 499 - 509. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. J. Behnke, D. J. Padilla, L. F. Ferreira, M. D. Delp, T. I. Musch, and D. C. Poole Effects of arterial hypotension on microvascular oxygen exchange in contracting skeletal muscle J Appl Physiol, March 1, 2006; 100(3): 1019 - 1026. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. S. Richardson, S. Duteil, C. Wary, D. W. Wray, J. Hoff, and P. G. Carlier Human skeletal muscle intracellular oxygenation: the impact of ambient oxygen availability J. Physiol., March 1, 2006; 571(2): 415 - 424. [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]
|
|
|
|
|
|
C. A. Kindig, B. Walsh, R. A. Howlett, C. M. Stary, and M. C. Hogan Relationship between intracellular PO2 recovery kinetics and fatigability in isolated single frog myocytes J Appl Physiol, June 1, 2005; 98(6): 2316 - 2319. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Kindig, R. A. Howlett, and M. C. Hogan Effect of contractile duration on intracellular PO2 kinetics in Xenopus single skeletal myocytes J Appl Physiol, May 1, 2005; 98(5): 1639 - 1645. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. McDonough, B. J Behnke, D. J Padilla, T. I Musch, and D. C Poole Control of microvascular oxygen pressures in rat muscles comprised of different fibre types J. Physiol., March 15, 2005; 563(3): 903 - 913. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Chung, P. A. Mole, N. Sailasuta, T. K. Tran, R. Hurd, and T. Jue Control of respiration and bioenergetics during muscle contraction Am J Physiol Cell Physiol, March 1, 2005; 288(3): C730 - C738. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. A. Kindig, C. M. Stary, and M. C. Hogan Effect of dissociating cytosolic calcium and metabolic rate on intracellular PO2 kinetics in single frog myocytes J. Physiol., January 15, 2005; 562(2): 527 - 534. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. J. Haseler, C. A. Kindig, R. S. Richardson, and M. C. Hogan The role of oxygen in determining phosphocreatine onset kinetics in exercising humans J. Physiol., August 1, 2004; 558(3): 985 - 992. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
