Influence of 14-day hind limb unloading on isolated muscle spindle activity in rats.

During hind limb unloading (HU), the soleus is often in a shortened position and the natural physiological stimulus of muscle spindles is altered, such that muscle spindle activity also changes. Using isolated spindle conditions, the present study investigates the electrophysiological activity and ultrastructure of muscle spindles following HU. Results show that muscle spindle discharges fall into either of two main patterns, single spikes or spike clusters in shortened positions, with a steady frequency of 18-38 spikes/s (mean 29.

Effects of hindlimb unloading and reloading on c-fos expression of spinal cord evoked by vibration of rat Achille tendon.

To determine whether the neuronal activity of the spindle cord in muscle spindle afferent pathways is altered after a period of hindlimb unloading (Hu), and after recovery, we focused on c-Fos-immunoreactivity in the spinal cord evoked by excitation of the muscle spindle in normal gravity and after 3, 7, and 14 days of Hu, and after 14 days of Hu with an additional 2, 5, and 9 days of unrestricted cage activity. High frequency sinusoidal vibration (HFV) applied to the Achilles tendon was used for activation of the muscle spindle. Results showed that c-Fos-immunoreactive neurons evoked by HFV were mainly concentrated in lamina IV-VII of the ipsilateral spinal cord.

[Effects of inosine injection in expression of myosin heavy chain in intrafusal and extrafusal myofibers in soleus muscle of tail-suspended rats].

Aim: To study the effects of inosine on myosin heavy chain (MHC) activity in rats soleus muscle after tail-suspension.

Methods: Weightlessness was simulated by tail-suspension of rats. Using immunohistochemistry technique, changes of expression of MHC in intrafusal and extrafusal fibers in soleus muscle were detected.

[Effects of Ligustrazine and Radix Astragali on activities of myosin adenosine triphosphatase of soleus muscle and muscle atrophy in tail-suspended rats].

Objective: To study the effects of Ligustrazine (Lig) and Radix Astragali (Rad) on activities of myosin adenosine triphosphatase (mATPase) of soleus muscle and atrophy in tail-suspended rat.

Method: Weightlessness was simulated by tail suspension in female rats. The activities of mATPase of intrafusal and extrafusal fibres in soleus muscle were detected by method of Ca2(+)-ATPase.

[Effects of high frequency vibration on expression of myosin heavy chain (MHC) in intrafusal and extrafusal fibers in soleus muscles of tail-suspended rats].

Objective: To study the effects of high frequency vibration on expression of myosin heavy chain (MHC) in intrafusal and extrafusal fibers in soleus muscles of tail-suspended rats.

Method: Weightlessness was simulated by tail suspension of female rats. Using immunohistochemistry technique, changes of expression of MHC in intrafusal and extrafusal fibers of soleus muscles were detected.

Effects of tail suspension on electrophysiological characteristics of muscle spindles in isolated rat soleus muscle.

Objective: To study changes in electrophysiological characteristics of muscle spindles induced by simulated weightlessness in isolated rats soleus.

Method: Weightlessness was simulated by tail-suspension in female rats. Using electro-physiological technique, the spontaneous discharge of muscle spindle and its response to ramp-and-hold stretch were observed in isolated soleus of 7 d, 14 d tail-suspended and control rats.

Effects of simulated weightlessness on myosin heavy chain expression of soleus intrafusal muscle fibers in rats.

Objective: To examine the myosin heavy chain expression in intrafusal fibers in rat soleus muscle before and after simulated weightlessness and to analyse the mechanism involved in muscle spindle deterioration during simulated weightlessness.

Method: The rats were divided into 3 groups: 7 d, 14 d tail-suspension group and control group. Control and experimental spindles were examined using monoclonal antibodies specific for myosin heavy chains of slow-tonic (ALD58) and fast-twitch (MF30) chicken muscles by the immunoperoxidase reaction utilizing the ABC (avidin-biotin-complex) method.

[Influence of simulated weightlessness on the morphology of nerve endings of muscle spindle in rat soleus muscle].

Objective: To study changes in structure and innervation of soleus muscle spindle in rats induced by simulated weightlessness.

Method: Weightlessness was simulated by tail suspension in female rats. The technique of Fawosky's Staining was used to detect the morphology of nerve endings of soleus muscle spindle in 7 d, 14 d, 21 d tail-suspended and control rats.

Effects of simulated weightlessness on Calbindin D-28K-immunoreactivity in rat soleus muscle spindle.

Objective. To analyze the mechanism involved in muscle spindle deterioration during simulated weightlessness. Method.

Acetylcholinesterase activity in soleus muscle intrafusal and extrafusal fibres in tail suspended rats.

Objective. To explore the mechanisms involved in muscle atrophy and conversion of the fiber types induced by simulated weightlessness. Method.

[Effects of simulated weightlessness on ultrastructure of soleus muscle spindle in rats].

Objective: To study changes in ultrastructure of soleus muscle spindle induced by simulated weightlessness in rats.

Method: Weightlessness was simulated by tail suspension in female rats. The ultrastructure of isolated soleus muscle spindle were observed in 4 d, 7 d, 14 d tail-suspended and 14 d recovered rats.