Red skeletal muscle exhibits the widest range of energy turnover of any tissue. It is therefore ideally suited to the study of controls of glycolsis, aerobic ATP production, and the interaction of the two on the regulation of ATP concentration. Present understanding is largely based on in vitro studies designed to solve pieces of the puzzle - i.e. feedback control of phosphofructokinase, control of the redex shuttle in mitochondria, etc. The success of such work permits a synthesis which explains how major pathways interact under physiologic conditions. The principal obstacle to in vivo metabolic studies has been inability to measure a complete set of metabolites including O2 per se simultaneously on a single preparation under various planned conditions of energy turnover. Metabolic and circulatory heterogeneities add further difficulties. The proposed experiments will be performed on a well-characterized dog gracilis preparation containing red fibers exclusively. All supply vessels are preserved in the vascular isolation. Intracellular PO2 and its regional distribution is measured with a cryomicrospectroscopic method with spatial resolution of 2-3 mitochondrial volumes. All assays of tissue metabolites are performed on the same samples used for O2 spectroscopy. Muscles are frozen in situ so all measurements are, in effect, simultaneous. Succunic dehydrogenase is used to scale for the oxidative capacity of each muscle. Thus some concerns about spatial and temporal heterogeneities and biologic variability can be overcome. Intracellular pH, cytosolic phosphorylation and redox potentials, glycolytic intermediates, O2, and parameters related to mitochondrial redox will be determined and correlated with rates of O2 consumption and glycolysis. Measurements will be made at rest, during rest-work transitions, during transitions between steady-state work rates during simulated excercise in the steady state and, if time permits, in recovery. Results will be used to evaluate current ideas of mitochondrial-cytosolic interaction and pathway control in vivo. The data will be used to develop and evaluate quantitative mathematical models of integrated energy metabolism in red muscle.

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Project (R01)
Project #
5R01AR036154-05
Application #
3157493
Study Section
Physiology Study Section (PHY)
Project Start
1986-04-01
Project End
1992-03-31
Budget Start
1990-04-01
Budget End
1992-03-31
Support Year
5
Fiscal Year
1990
Total Cost
Indirect Cost
Name
University of Rochester
Department
Type
Schools of Dentistry
DUNS #
208469486
City
Rochester
State
NY
Country
United States
Zip Code
14627
Honig, C R; Connett, R J; Gayeski, T E (1992) Interaction of blood flow, diffusive transport and cell metabolism in isovolemic anemia. Adv Exp Med Biol 316:21-9
Honig, C R; Connett, R J; Gayeski, T E (1992) O2 transport and its interaction with metabolism;a systems view of aerobic capacity. Med Sci Sports Exerc 24:47-53
Stanley, W C; Connett, R J (1991) Regulation of muscle carbohydrate metabolism during exercise. FASEB J 5:2155-9
Funk, C I; Clark Jr, A; Connett, R J (1990) A simple model of aerobic metabolism: applications to work transitions in muscle. Am J Physiol 258:C995-1005
Connett, R J; Honig, C R; Gayeski, T E et al. (1990) Defining hypoxia: a systems view of VO2, glycolysis, energetics, and intracellular PO2. J Appl Physiol 68:833-42
Funk, C; Clark Jr, A; Connett, R J (1989) How phosphocreatine buffers cyclic changes in ATP demand in working muscle. Adv Exp Med Biol 248:687-92
Connett, R J; Honig, C R (1989) Regulation of VO2 in red muscle: do current biochemical hypotheses fit in vivo data? Am J Physiol 256:R898-906
Connett, R J (1989) In vivo control of phosphofructokinase: system models suggest new experimental protocols. Am J Physiol 257:R878-88
Connett, R J (1988) The cytosolic redox is coupled to VO2. A working hypothesis. Adv Exp Med Biol 222:133-42
Connett, R J (1988) Analysis of metabolic control: new insights using scaled creatine kinase model. Am J Physiol 254:R949-59

Showing the most recent 10 out of 12 publications