This project is designed to determine the relationship between the physiological properties of individual motor units and certain key biochemical properties of the unit's constituent muscle fibers. A collaboration has been established between two laboratories, one engaged in quantitative single cell biochemistry, the other in spinal cord electrophysiology. The experimental approach is 1) to determine physiological characteristics of whole motor units, both nerve and muscle components, 2) to identify those units by a glycogen depletion technique, 3) to dissect segments of the identified unit fibers, and 4) to analyze these for selected metabolic enzymes. (The capability to identify motor unit fibers and to biochemically analyze single fibers from muscle cross-sections is a major advantage of this application.) The primary aim is to functionally correlate some aspects of energy metabolism with physiological properties of motor aspects of energy metabolism with physiological properties of motor units. In addition to the major purpose, it is expected that practical information will be gained about muscle fiber classification systems. The objectives of this work bear on a fundamental issue in neuromuscular interactions: the identity of the undelrying biochemical properties of muscle that govern its physiological capacity. The study of motor units has contributed importantly to this issu7e. The proposed study would refine our understanding of motor units. The ultimate health-related value of this work is to provide clues to the etiology of diseases which affect muscle performance.
| Stauffer, E K; McDonagh, J C; Hornby, T G et al. (2007) Historical reflections on the afterhyperpolarization--firing rate relation of vertebrate spinal neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 193:145-58 |
| Gorman, R B; McDonagh, J C; Hornby, T G et al. (2005) Measurement and nature of firing rate adaptation in turtle spinal neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 191:583-603 |
| Stauffer, E K; Stuart, D G; McDonagh, J C et al. (2005) Afterhyperpolarization-firing rate relation of turtle spinal neurons. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 191:135-46 |
| Callister, Robert J; Sesodia, Sanjay; Enoka, Roger M et al. (2004) Fatigue of rat hindlimb motor units: biochemical-physiological associations. Muscle Nerve 30:714-26 |
| McDonagh, J C; Callister, R J; Favron, M L et al. (2004) Resistance to disuse atrophy in a turtle hindlimb muscle. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 190:321-9 |
| Callister, R J; Donnelly, R P; Pierce, P A et al. (1996) Motor pool organization of the external gastrocnemius muscle in the turtle, Pseudemys (Trachemys) scripta elegans. J Morphol 227:171-83 |
| Callister, R J; Laidlaw, D H; Stuart, D G (1995) A commentary on the segmental motor system of the turtle: implications for the study of its cellular mechanisms and interactions. J Morphol 225:213-27 |
| Laidlaw, D H; Callister, R J; Stuart, D G (1995) Fiber-type composition of hindlimb muscles in the turtle, Pseudemys (Trachemys) scripta elegans. J Morphol 225:193-211 |
| Sesodia, S; Choksi, R M; Nemeth, P M (1994) Nerve-dependent recovery of metabolic pathways in regenerating soleus muscles. J Muscle Res Cell Motil 15:573-81 |
| Rosser, B W; Norris, B J; Nemeth, P M (1992) Metabolic capacity of individual muscle fibers from different anatomic locations. J Histochem Cytochem 40:819-25 |
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