This research aims to increase our understanding of sensory transduction in somatic mechanoreceptors. Such receptors subserve a wide variety of sensory systems which convert mechanical forces to neural signals which are transmitted to the central nervous system. Very little information is available on the fundamental steps of the transduction process. We propose a study on the primary ending of the isolated mammalian muscle spindle which is an especially favorable preparation for a direct approach on the problem because of: the ability to study it in isolation, the relatively large size of the myelinated branches and their terminals, the accessibility of structures in our isolated decapsulated preparation and the ability to visualize its structure microscopically. Using newly developed techniques of imaging and patch clamping, we will investigate: 1) the conductance changes which occur in the nerve terminals in response to mechanical stress and the characteristics of stretch-activated channels. 2) the spread of potentials produced by the conductance changes along the myelinated branches of the ending and the site of impulse initiation, and 3) a quantitative study of the structure of the primary ending both its myelinated branches and unmyelinated terminals, which will allow us to derive an electrical model of the ending. This is essential for the interpretation of an understanding of the overall transduction process in the ending. Knowledge of the basic mechanisms of transduction may be very important for the understanding of many disorders affecting sensory systems.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS007907-26
Application #
2260683
Study Section
Neurology B Subcommittee 2 (NEUB)
Project Start
1979-01-01
Project End
1994-12-31
Budget Start
1993-01-01
Budget End
1994-12-31
Support Year
26
Fiscal Year
1993
Total Cost
Indirect Cost
Name
Washington University
Department
Physiology
Type
Schools of Medicine
DUNS #
062761671
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
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Petit, J; Filippi, G M; Emonet-Denand, F et al. (1990) Changes in muscle stiffness produced by motor units of different types in peroneus longus muscle of cat. J Neurophysiol 63:190-7
Petit, J; Filippi, G M; Gioux, M et al. (1990) Effects of tetanic contraction of motor units of similar type on the initial stiffness to ramp stretch of the cat peroneus longus muscle. J Neurophysiol 64:1724-32
Duncan, M J; Takahashi, J S; Dubocovich, M L (1989) Characteristics and autoradiographic localization of 2-[125I]iodomelatonin binding sites in Djungarian hamster brain. Endocrinology 125:1011-8
Duncan, M J; Takahashi, J S; Dubocovich, M L (1988) 2-[125I]iodomelatonin binding sites in hamster brain membranes: pharmacological characteristics and regional distribution. Endocrinology 122:1825-33
Emonet-Denand, F; Hunt, C C; Petit, J et al. (1988) Proportion of fatigue-resistant motor units in hindlimb muscles of cat and their relation to axonal conduction velocity. J Physiol 400:135-58
Azerad, J; Hunt, C C; Laporte, Y et al. (1986) Afferent fibres in cat ventral roots: electrophysiological and histological evidence. J Physiol 379:229-43
Adal, M N (1986) The transverse tubular system of cat intrafusal muscle fibres. Cell Tissue Res 244:197-202
Emonet-Denand, F; Hunt, C C; Laporte, Y (1985) Fusimotor after-effects on responses of primary endings to test dynamic stimuli in cat muscle spindles. J Physiol 360:187-200
Emonet-Denand, F; Hunt, C C; Laporte, Y (1985) Effects of stretch on dynamic fusimotor after-effects in cat muscle spindles. J Physiol 360:201-13