The Experts below are selected from a list of 9 Experts worldwide ranked by ideXlab platform
M. Fischer - One of the best experts on this subject based on the ideXlab platform.
-
Research report E ffects of the calcium antagonist nifedipine on the afferent impulse activity of isolated cat muscle spindles
2002Co-Authors: M. FischerAbstract:The impulse activity of muscle spindles isolated from the cat tenuissimus muscle was investigated under varying concentrations of the L-type calcium channel blocker nifedipine. At a concentration of 25 mM nifedipine impulse activity was clearly diminished in both primary and secondary endings. However, low concentrations of the drug (5-10 mM) exerted unexpected excitatory effects. The dynamic properties of primary endings in particular were augmented; those of secondary endings were also increased, although only slightly. A detailed analysis of the afferent discharge patterns obtained under ramp-and-hold stretches yielded the following effects of 10 mM nifedipine. (1) The initial burst at the beginning of the ramp phase of a stretch was increased in primary endings; (2) the peak dynamic discharge frequency at the end of the ramp phase was considerably increased in most primary endings; (3) the sensitivity of the peak dynamic discharge value to varying amplitudes and velocities of stretch was significantly enhanced in primary endings, and also increased, although only slightly, in secondary endings; (4) the rise in the discharge frequency during the ramp phase of a stretch was augmented in both types of ending, the effect being again stronger in primary endings; (5) the fast adaptive decay of the impulse frequency following the ramp phase of a ramp-and-hold stretch was significantly increased in primary endings, but remained unaffected in secondary endings. The enhanced dynamic properties of primary endings were also observed under small sinusoidal stretch stimuli (10 mm, 40 Hz), where nifedipine induced a significant shift in the position of the 1:1 driven action potentials toward smaller phase values. In view of an increase in tension in the isolated muscle spindle and an increased initial burst in primary endings in the presence of nifedipine, it is suggested that the drug facilitates the attachment of cross-bridges in the poles of the intrafusal muscle Fibers. The increase in the dynamic properties of primary endings points to the possibility that the drug preferentially affects the Nuclear Bag Fiber. The 1 inhibitory effect on the afferent discharge rate at high doses of the drug is interpreted as the consequence of a calcium channel block in 21 the membranes of the sensory endings. The membrane potential of sensory endings appears to be highly dependent on sustained Ca conductance.
Jon M. Walro - One of the best experts on this subject based on the ideXlab platform.
-
Axotomy induces fusimotor-free muscle spindles in neonatal rats
Neuroscience Letters, 1992Co-Authors: Jan Kucera, Jon M. WalroAbstract:Abstract Crushing the nerve to the medial gastrocnemius (MG) muscle at birth and administering nerve growth factor to rats afterwards results in a reinnervated muscle with supernumerary muscle spindles, some of which must have formed de novo. Structure and innervation of spindles in the reinnervated MG muscles were studied in serial 1 μm transverse sections. Two types of spindle-like encapsulations were observed. The prevalent type consisted of one to three small diameter intrafusal Fibers with features of Nuclear chain Fibers or infrequently a Nuclear Bag Fiber. The second type of encapsulation consisted of the small-diameter Fibers located in a compartment which abutted a compartment containing a large diameter extrafusal Fiber. All intrafusal Fibers in spindles of the experimental muscles were innervated by afferents, but most of them (85%) were devoid of efferent innervation. Thus, immature fusimotor neurons may be more susceptible than spindle afferents to cell death after axotomy at birth.
Jan Kucera - One of the best experts on this subject based on the ideXlab platform.
-
Axotomy induces fusimotor-free muscle spindles in neonatal rats
Neuroscience Letters, 1992Co-Authors: Jan Kucera, Jon M. WalroAbstract:Abstract Crushing the nerve to the medial gastrocnemius (MG) muscle at birth and administering nerve growth factor to rats afterwards results in a reinnervated muscle with supernumerary muscle spindles, some of which must have formed de novo. Structure and innervation of spindles in the reinnervated MG muscles were studied in serial 1 μm transverse sections. Two types of spindle-like encapsulations were observed. The prevalent type consisted of one to three small diameter intrafusal Fibers with features of Nuclear chain Fibers or infrequently a Nuclear Bag Fiber. The second type of encapsulation consisted of the small-diameter Fibers located in a compartment which abutted a compartment containing a large diameter extrafusal Fiber. All intrafusal Fibers in spindles of the experimental muscles were innervated by afferents, but most of them (85%) were devoid of efferent innervation. Thus, immature fusimotor neurons may be more susceptible than spindle afferents to cell death after axotomy at birth.
Tuanting Zhang - One of the best experts on this subject based on the ideXlab platform.
-
Electron Microscopy Technology and It’s Application in the Morphology
Lecture Notes in Electrical Engineering, 2013Co-Authors: Xiaohong Li, Zhou Li, Tuanting ZhangAbstract:Objective To observe the influence of different load on the rat gastrocnemius muscle spindle of shape and structure. Methods Adopt swimming training model. Medium load group swim 60 min each day. Over load group, loaded with the weight of 5 %, swim 60 min each day, 6 days a week. Adopt muscle spindle of Faworky’s display and electron microscopy techniques; observe changes of different load training on the rat gastrocnemius muscle spindle shape and structure. Results show that gastrocnemius muscle spindle form is smaller, while muscle spindle structure is normal. In medium load group muscle spindle structure is integrate, spindle extrinsic is aligned, muscle spindle in neural myelin structure are clear and complete, Nuclear Bag Fiber, Nuclear chain Fiber diameter than the control group significantly increases. In over load group spindle body increased obviously, inside and outside is separated by capsule seriously. Muscle fibrils quantity is less, sac cells are swollen, axis clearance increased obviously, spindle in neural axis lining and myelin has separated. These preliminary findings indicate medium load movement could significantly improve muscle spindle shape and structure, while over load sports training could lead to pathological changes of muscle spindle structure.
Xiaohong Li - One of the best experts on this subject based on the ideXlab platform.
-
Electron Microscopy Technology and It’s Application in the Morphology
Lecture Notes in Electrical Engineering, 2013Co-Authors: Xiaohong Li, Zhou Li, Tuanting ZhangAbstract:Objective To observe the influence of different load on the rat gastrocnemius muscle spindle of shape and structure. Methods Adopt swimming training model. Medium load group swim 60 min each day. Over load group, loaded with the weight of 5 %, swim 60 min each day, 6 days a week. Adopt muscle spindle of Faworky’s display and electron microscopy techniques; observe changes of different load training on the rat gastrocnemius muscle spindle shape and structure. Results show that gastrocnemius muscle spindle form is smaller, while muscle spindle structure is normal. In medium load group muscle spindle structure is integrate, spindle extrinsic is aligned, muscle spindle in neural myelin structure are clear and complete, Nuclear Bag Fiber, Nuclear chain Fiber diameter than the control group significantly increases. In over load group spindle body increased obviously, inside and outside is separated by capsule seriously. Muscle fibrils quantity is less, sac cells are swollen, axis clearance increased obviously, spindle in neural axis lining and myelin has separated. These preliminary findings indicate medium load movement could significantly improve muscle spindle shape and structure, while over load sports training could lead to pathological changes of muscle spindle structure.
