PMID- 17942641
OWN - NLM
STAT- MEDLINE
DCOM- 20080221
LR  - 20200930
IS  - 0363-6143 (Print)
IS  - 0363-6143 (Linking)
VI  - 294
IP  - 1
DP  - 2008 Jan
TI  - Linear relation between time constant of oxygen uptake kinetics, total creatine, 
      and mitochondrial content in vitro.
PG  - C79-87
AB  - Following the onset of moderate aerobic exercise, the rate of oxygen consumption 
      (J(o)) rises monoexponentially toward the new steady state with a time constant 
      (tau) in the vicinity of 30 s. The mechanisms underlying this delay have been 
      studied over several decades. Meyer's electrical analog model proposed the 
      concept that the tau is given by tau = R(m) x C, where R(m) is mitochondrial 
      resistance to energy transfer, and C is metabolic capacitance, determined 
      primarily by the cellular total creatine pool (TCr = phosphocreatine + creatine). 
      The purpose of this study was to evaluate in vitro the J(o) kinetics of isolated 
      rat skeletal muscle mitochondria at various levels of TCr and mitochondrial 
      protein. Mitochondria were incubated in a medium containing 5.0 mM ATP, TCr pools 
      of 0-1.5 mM, excess creatine kinase, and an ATP-splitting system of glucose + 
      hexokinase (HK). Pyruvate and malate (1 mM each) were present as oxidative 
      substrates. J(o) was measured across time after HK was added to elicit one of two 
      levels of J(o) (40 and 60% of state 3). At TCr levels (in mM) of 0.1, 0.2, 0.3, 
      0.75, and 1.5, the corresponding tau values (s, means +/- SE) were 22.2 +/- 3.0, 
      36.3 +/- 2.2, 65.7 +/- 4.3, 168.1 +/- 22.2, and 287.3 +/- 25.9. Thus tau 
      increased linearly with TCr (R(2) = 0.916). Furthermore, the experimentally 
      observed tau varied linearly and inversely with the mitochondrial protein added. 
      These in vitro results consistently conform to the predictions of Meyer's 
      electrical analog model.
FAU - Glancy, Brian
AU  - Glancy B
AD  - Department of Kinesiology, Arizona State University, Tempe, AZ 85287-0404, USA.
FAU - Barstow, Thomas
AU  - Barstow T
FAU - Willis, Wayne T
AU  - Willis WT
LA  - eng
PT  - Journal Article
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PT  - Validation Study
DEP - 20071017
PL  - United States
TA  - Am J Physiol Cell Physiol
JT  - American journal of physiology. Cell physiology
JID - 100901225
RN  - 0 (Malates)
RN  - 817L1N4CKP (malic acid)
RN  - 8558G7RUTR (Pyruvic Acid)
RN  - 8L70Q75FXE (Adenosine Triphosphate)
RN  - EC 2.7.1.1 (Hexokinase)
RN  - EC 2.7.3.2 (Creatine Kinase)
RN  - IY9XDZ35W2 (Glucose)
RN  - MU72812GK0 (Creatine)
SB  - IM
CIN - Am J Physiol Cell Physiol. 2008 Sep;295(3):C844-6; author reply C847-8. PMID: 
      18776157
MH  - Adenosine Triphosphate/metabolism
MH  - Animals
MH  - Creatine/*metabolism
MH  - Creatine Kinase/metabolism
MH  - Glucose/metabolism
MH  - Hexokinase/metabolism
MH  - In Vitro Techniques
MH  - Kinetics
MH  - Linear Models
MH  - Malates/metabolism
MH  - Male
MH  - Mitochondria, Muscle/*metabolism
MH  - Models, Biological
MH  - Muscle, Skeletal/*metabolism
MH  - *Oxidative Phosphorylation
MH  - *Oxygen Consumption
MH  - Physical Exertion/*physiology
MH  - Pyruvic Acid/metabolism
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Reproducibility of Results
EDAT- 2007/10/19 09:00
MHDA- 2008/02/22 09:00
CRDT- 2007/10/19 09:00
PHST- 2007/10/19 09:00 [pubmed]
PHST- 2008/02/22 09:00 [medline]
PHST- 2007/10/19 09:00 [entrez]
AID - 00138.2007 [pii]
AID - 10.1152/ajpcell.00138.2007 [doi]
PST - ppublish
SO  - Am J Physiol Cell Physiol. 2008 Jan;294(1):C79-87. doi: 
      10.1152/ajpcell.00138.2007. Epub 2007 Oct 17.