American Journal of Physiology; Regulatory, Integrative and Comparative Physiology Final accepted version Tension- and Afferent-input-associated Responses of Neuromuscular System of Rats to Hindlimb Unloading and/or Tenotomy

p. 51, 2002.33. Williams PE, and Goldspink G. Changes in sarcomeres length and physiologicalproperties in immobilized muscle. J Anat 127: 459-468, 1978.34. Winiarski AM, Roy RR, Alford EK, Chiang PC, and Edgerton VR. Mechanicalproperties of rat skeletal muscle after hindlimb suspension. Exp Neurol 96: 650-660, 1987. R-00694-2003, R228Table 1 The changes in the body weight and the amount of food intake during the experiment 2. Mean±SEM. n=5 in each group. Pl, plantaris; MG, medial gastrocnemius; LG, lateral gastrocnemius; TA, tibialis anterior; EDL, extensor digitorumlongus.Day of the experiment1st ~ 2nd ~ 3rd ~ 4th ~ 5th ~ 6th ~ 7thRecordingNoneNoneNonePerformedPerformedPerformedPerformed TreatmentsNoneElectrodeimplantationNoneTenotomyof Pl, MGand LGTenotomyof TA andEDLTenotomyof soleusKilled AnesthesiaNonePerformedNonePerformedPerformedPerformedPerformed Control 305±2.7307±5.5306±3.9309±3.2312±2.8313±3.3315±1.8Body weight(g) Experimental 305±1.3305±3.6309±2.5310±2.2311±4.0310±2.5312±2.6 Control23±1.521±1.522±1.822±1.320±1.521±2.3Food intake(g/day) Experimental23±2.522±2.321±3.523±1.522±2.323±1.5 R-00694-2003, R229FIGURE LEGENDSFigure 1: The location (upper illustration) and typical pattern (bottom picture) of nuclearyellow-labeled motoneurons in the longitudinal section of the rat spinal cord. Thenumbers of labeled motoneurons in one rat are shown in the parentheses. Totalnumbers of motoneurons detected in 5 rats are 168, 269, 236, 313, 197, and 164 forEDL, MG, TA, LG, Pl, and soleus, respectively. The numbers 4-6 indicate thesegmental levels of the spinal cord. EDL, extensor digitorum longus; MG, medialgastrocnemius; TA, tibialis anterior; LG, lateral gastrocnemius; Pl, plantaris. Thearrows in the bottom picture indicate the nuclear yellow-labeled motoneurons. WM,white matter; GM, gray matter; R, rostral direction; M, medial direction. Scale bar =100 μm. Figure 2: Typical patterns of afferent and efferent neurograms recorded at the L5 segmentallevel of the spinal cord and electromyogram (EMG) activities of soleus, medialgastrocnemius (MG), and tibialis anterior (TA) during quadrupedal posture on the floorand 20-second of hindlimb suspension before tenotomy (upper-left), after tenotomy ofMG, LG and Pl (upper-right), of MG, LG, Pl, TA and EDL (lower-left), and of MG, LG,Pl, TA, EDL and soleus (lower-right). LG, lateral gastrocnemius; Pl, plantaris; EDL,extensor digitorum longus. Figure 3: The integrated levels of afferent (A) and efferent (B) neurograms andelectromyogram (EMG) of soleus (C), medial gastrocnemius (D) and tibialis anterior(E) during quadrupedal posture on the floor and 20-second of hindlimb suspension in 5rats. Mean ± SEM. *, §, †, ‡, and : Significantly different from the level beforehindlimb suspension (on the floor, pre) among the respective group indicated by thespecific bar, during hindlimb suspension among the respective group indicated by the R-00694-2003, R230specific bar, control (before tenotomy, white bars), after tenotomy of MG, LG and Pl(grey bars), and of MG, LG, Pl, TA and EDL (black bars), respectively (p<0.05). Thebaseline levels of these neuromuscular activities are shown by the horizontal brokenlines. The baseline activities were checked after the spinal transection at the L3 and L6segmental levels, including dorsal and ventral roots, after the end of experiment. All ofthe values shown in the figure were significantly greater than the baseline activities(p<0.05). MG, medial gastrocnemius; LG, lateral gastrocnemius; Pl, plantaris; TA,tibialis anterior; EDL, extensor digitorum longus. Figure 4: The relationship between the integrated levels of soleus electromyogram (EMG)and afferent neurogram at the L5 segmental level of the spinal cord. MG, medialgastrocnemius; LG, lateral gastrocnemius; Pl, plantaris; TA, tibialis anterior; EDL,extensor digitorum longus. Figure 5: Changes in the integrated levels of afferent (open circle) and efferent (closedcircle) neurograms and soleus electromyogram (EMG, gray bar) before and during14-day hindlimb suspension in 10 rats. Mean ± SEM.: Significantly different fromthe pre-suspension level recorded at quadrupedal posture on the floor (p<0.05). Figure 6: The relationship between the anterior angle of ankle joint and passive and activetension development (A, n=5 for each group) and the mean in vivo length of sarcomeres(B, 10 rats for each group and 5 muscles or 5x30 fibers for each angle) before and after14-day hindlimb suspension. The total sarcomere number per fiber is also illustrated(C, 5 muscles or 5x60 fibers for each group). Mean ± SEM. * and : Significantlydifferent from the pre-suspension control and the levels at 160 ankle joint angle(p<0.05). R-00694-2003, R231 Figure 7: The distribution of soleus muscle fibers with various lengths before and after 14days of hindlimb suspension. Five muscles or 5x60 fibers for each group. Figure 8: The distribution of soleus muscle fibers with various sarcomere lengths at 160 ofankle joint angle before and after 14 days of hindlimb suspension. Five muscles or5x30 fibers for each group. R-00694-2003, R232