Journal of the Neurological Sciences, 1979, 41 : 39-54 © Elsevier/North-Holland Biomedical Press

39

E F F E C T OF T E N O T O M Y O N S E L F - R E I N N E R V A T E D A N D R A N D O M L Y R E I N N E R V A T E D SOLEUS M U S C L E OF R A T

TERESA RYMASZEWSKA-KOSSAKOWSKA 1, CATHERINE SOUCHIER~, ADAM ~LIWOWSKI1 and JEAN-CLAUDE CZYBA z 1Department of Histology and Embryology, Institute of Biostructure, Medical Academy, Warsaw (Poland), and 2Laboratoire d'Histologie et Embryologie ; U.E.R. M(dicale Grange-Blanche, Universitd Claude-Bernard, Lyon (France)

(Received 4 September, 1978) (Accepted 11 October, 1978)

SUMMARY The time course and degree of atrophic changes caused by tenotomy were compared in normal, self-reinnervated and randomly reinnervated soleus muscle 6 months after transsection and reunion of the nerve at different distances from the muscle. Comparison was made between the behaviour of Type I and Type II fibers, distinguished on the basis of histochemical myofibrillar ATPase and succinic dehydrogenase reactions. Cross-sectional areas of individual muscle fibers were measured using Quantimet 720 image analyser. Selective atrophy of Type I muscle fibers as determined by structural and histochemical changes was observed after tenotomy of normal, self-reinnervated and randomly reinnervated soleus muscles after transsection of the muscular branch of the tibial nerve. Type II muscle fibers in randomly reinnervated muscles were found to be relatively insensitive to tenotomy, as in normal muscle. In randomly reinnervated muscles after transsection and reunion of the sciatic nerve, tenotomy did not cause any visible structural and histochemical abnormalities although a decrease of muscle weight and cross-sectional surface area of fibers was noted. Since in these muscles Type II fibers increased to about 70 ~ of the muscle fiber population, it is suggested that the increased percentage of Type II fibers seemed to prevent the atrophic changes in Type I fibers after tenotomy.

INTRODUCTION It has been demonstrated in various animal species that the soleus, a tonic muscle, is more severely affected following tenotomy than other leg muscles (Eccles 1944; This work was partially supported by grant No. 10.4 from the Polish Academy of Sciences.

40 McMinn and Vrbovfi 1962, 1964; Nelson 1969). This is attributable to the predominance of Type I fibers (low myosin ATPase activity) which undergo a more rapid and marked degeneration than Type lI fibers (high myosin ATPase activity) (Engel et al. 1966; Tomanek and Cooper 1972). The cause of this different behaviour of the two basic types of muscle fibers is not fully understood. It is not clear whether it is based on some intrinsic properties of muscle fibers, specific for the given fiber type or whether it is induced by different properties of the motor neurones. The soleus muscle of normal adult rat is composed primarily of Type I fibers with a small percentage of Type II fibers (Karpati and Engel 1967; Pullen 1977). Crossreinnervation as well as random reinnervation produces an increase of the percentage of Type II fibers (Yellin 1967; Guth and Samaha 1969; Rymaszewska-Kossakowska and gliwowski 1977), its intensity depending on the level at which the nerve is injured and reunited (Rymaszewska-Kossakowska and gliwowski, in preparation). Newly formed Type II fibers arise probably by synthesis of a molecularly different form of ATPase (Samaha et al. 1970; Mommaerts et al. 1977) in a certain number of Type I fibers under the influence Type II motor neurones normally destined for "white" type muscle (Kugelberg 1976). The aim of the present paper was to establish: (1) Whether the modification of the cytoenzymaticcharacteristics of muscle fibers will influence their sensitivity to disuse caused by tenotomy, that is, whether newly formed Type II fibers will become relatively insensitive to tenotomy, as they are in normal muscle; (2) Whether the increased percentage of Type II fibers in randomly reinnervated soleus muscle will influence the behaviour of Type I fibers after tenotomy. For this purpose tenotomized normal soleus muscles were compared with tenotomized self-reinnervated and randomly reinnervated ones on the basis of histochemical and morphometric observations with the use of image analysis (Scott and Hoy 1976; Jaffe et al. 1978). MATERIALAND METHODS Male Wistar rats 8-10 weeks old, weighing 180-200 g were used. Surgery was performed unilaterally in aseptic conditions under pentobarbital (Nembutal) anaesthesia. Muscles from the contralateral side served as controls. Two types of experiment were done: (a) tenotomy, (b) tenotomy performed six months after transsection and reunion of the nerve at different distances from the soteus muscles. Animals were divided into 4 groups : Group 1 (tenotomy) animals being kept for 6 months in analogous conditions to those from the remaining 3 groups and then subjected to tenotomy of soleus muscle. Group 2 (self-reinnervation and tenotomy) animals with soleus nerve transsected close to the muscle. The proximal and distal stumps were "glued" with fibrinogen, thrombin and a drop of Ringer's solution. The composition of Ringer's solution was that described by Liley (1965). Group 3 (random reinnervation and tenotomy) animals with a muscular branch

41 of the tibial nerve cut just above the branch supplying the lateral head of the gastrocnemius. The proximal and distal stumps were joined as described above. Group 4 (random reinnervation and tenotomy) animals with sciatic nerve transsected at the trochanter level. Proximal and distal stumps were joined by single sutures (Ethicon 10-0 silk). Tenotomy was performed by dissecting the muscle free of its insertion into the Achilles tendon and about 3 mm of tendon was excised. The animals were killed 1, 3, 7 and 14 days after tenotomy. The soleus muscles were dissected out and weighed. Fragments from the middle part of the muscle belly were prepared, frozen in isopentane at --155 °C and serial cross-sections about 10 #m thick were obtained in the cryostat. They were then stained with haematoxylin-eosin or treated by histochemical techniques for succinic dehydrogenase (Nachlas et al. 1957) and myofibriltar adenosine triphosphatase with acid (pH 4.35) and alkaline (pH 10.4) preincubation (Guth and Samaha 1970). Type I and Type II fibers were classified according to Brooke and Kaiser (1970). The percentage of Type I and Type II fibers was determined by counting the number of light (Type I) and dark (Type II) cells in the entire cross-sections of muscles after alkali preincubation. Subclasses of Type II fibers were not distinguished, and fibers with intermediate staining intensities were classified as Type II fibers. Estimation of the percentage of the two basic types of fiber was done in groups of animals with soleus muscle tenotomized 1 day earlier. The cross-sectional areas of Type I and Type II fibers were measured by an image analyser (Quantimet 720, Cambridge Instruments, England). Thirty-six fibers of each type randomly selected from the central region of the cross-section of the muscle were measured on each slide. The image of the muscle fibers was relayed to the viewing screen by a 720-line plumbicon scanner, and individual muscle fibers were detected with the use of the light pen (Scott and Hoy 1976). The data were processed statistically as follows: (1) The mean cross-sectional area and the mean standard deviation were determined for all samples (each composed of 36 fibers) for both fiber types in operated and contralateral soleus muscles. (2) The mean cross-sectional area of each type of fiber of the tenotomized muscle was compared with the area of fibers of the contralateral muscle by means of simple Student's t-test. (3) The effect of the tenotomy is represented by the mean cross-sectional area of the 36 fibers of the operated muscle expressed as the percentage of control values from the contralateral leg. This made a comparison between animals possible. For each group of animals and for each day a grand mean was determined: that is the mean of individual means. (4) Non-parametric Mann-Whitney test was performed to indicate the significant changes. RESULTS Histochemical observations The relative number of Type II fibers in normal and reinnervated soleus muscle

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Fig. 1. Comparison of the percentage of Type I! fibers in control intact soleus muscle (1), self-reinnerrated soleus muscle 6 months after transsection and reunion of the soleus nerve (2), randomly reinnervated soleus muscle 6 months after transsection and reunion of the muscular branch of tibial nerve (3) and randomly reinnervated soleus muscle 6 months after transsection and suturing of the sciatic nerve (4). Each bar represents the mean value ± SE obtained from 4 to 7 rats' soleus muscles.

43

Fig. 2. Dynamics of changes in succinic dehydrogenase activity in tenotomized soleus muscle. A : one day after tenotomy, irregular distribution and areas devoid of enzymatic activity in Tyl:e I fibers are seen. B: 7 days after tenotomy, target fiber of Type I with three zones: inner zone with low activity, middle zone with very strong activity and outer zone with intermediate activity can be recognized, Type II fiber (dark) shows regular distribution of enzymatic activity. C: 14 days after tenotomy, irregular distribution of succinic dehydrogenase activity in both Type I and Type II fibers is seen. The arrows indicate Type II fibers, x 250.

44 6 months after nerve surgery is shown in Fig. 1. This value amounts to 11.7 :~: 2.3 '.',,i in control intact muscle, decreasing to 0.4 ± 0.2 in self-reinnervated soleus muscle and increasing to 31.1 ~ 1.9 after transsection and reunion of the muscular branch of the tibial nerve, and to 69.8 ± 1.8 after transsection and reunion of the sciatic nerve. In the group of animals with normal tenotomized soleus muscle (group 1), areas devoid of succinic dehydrogenase activity in Type I fibers were noted as early as one day after transsection of the tendon, giving rise to a foam-like pattern of muscle fiber structure. These changes involved exclusively Type I fibers, whereas the Type II fibers seemed to be unchanged (Fig. 2A). After 3 days most of Type I fibers showed areas devoid of succinic dehydrogenase activity. Distribution of the succinic dehydrogenase reaction product in Type I fibers was quite different at the 7th day after tenotomy. The fibers had a central lightly stained zone, surrounded by a densely stained intermediate zone and a relatively normal peripheral region, corresponding to so-called target fibers. Type II fibers continued to show no changes (Fig. 2B). Fourteen days after tenotomy irregular distribution of succinic dehydrogenase activity was found nearly in all Type I fibers and also in some Type II fibers (Fig. 2C). In the sections stained with haematoxylin-eosin acute necrosis with phagocytosis was observed in some fibers as early as one day after tenotomy, these changes disappearing between the 3rd and 7th day after the operation. When tenotomy was performed following self-reinnervation of the muscle after section and reuniting of the soleus nerve (group 2) all the above described enzymatic changes were seemingly more pronounced, particularly on 1 day after tenotomy. The increased number of fibers undergoing acute necrosis with phagocytosis was observed

Fig. 3. Self-reinnervatedsoleus muscleone day after tenotomy, two abnormally large coil fibers showing variation in succinic dehydrogenase activity. × 250.

Fig. 4. Serial cross-sections of randomly reinnervated soleus muscle after transsection and reunion of the muscular branch of tibial nerve, 7 days after tenotomy. A: succinic dehydrogenase, B: ATPase following preincubation at pH 10.4. Targets in grouped Type I fibers are seen, while grouped Tylze 11 fibers do not show any abnormalities, x 126.

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46 1 a n d 3 days after t e n o t o m y . Also a n increased n u m b e r of snake-coil fibers, usually a b n o r m a l l y large, was n o t e d (Fig. 3). The soleus muscle reinnervated r a n d o m l y after transsection a n d reuniting of the m u s c u l a r b r a n c h of the tibial nerve (group 3) showed g r o u p i n g of fibers, uniform, as regards cytoenzymatic character, typical of the r e i n n e r v a t i o n process. Type I fibers exhibited a n a l o g o u s changes in succinic dehydrogenase a n d ATPase activity to those o f t e n o t o m y of n o r m a l a n d self-reinnervated muscles. Snake-coils a n d fibers u n d e r g o i n g phagocytosis were also observed, b u t n o t so frequently as in self-reinnervated t e n o t o m ized muscle. Type II fibers did n o t show a n y abnormalities until the 7th day (Figs. 4A a n d B). F o u r t e e n days after t e n o t o m y target fibers appeared also in some Type II fibers. The soleus muscle r a n d o m l y reinnervated after transsection a n d r e u n i o n of the sciatic nerve (group 4) behaved quite differently after t e n o t o m y . To the end of the observation period n o distinctly a b n o r m a l fibers were found. After 7 and 14 days only

TABLE 1 SIMPLE t-TEST VALUES WHICH REPRESENT A COMPARISON OF 36 FIBER AREAS OF EACH TYPE ON THE TENOTOMIZED SIDE AND THE CONTROL ONE OF EACH RAT Any value above 1.96 is significant at 95 ~ confidence limits (0.05 level). Animal 1 fibers TypeI

Animal 2 fibers

TypelJ[ TypeI

Animal 3 fibers Typell Typel

Group 1 Day 0 1.25 1.88 --3.17 ~4.80 0.40 5.43 5.85 Day 1 16.13 12.58 6.69 5.59 7.99 Day 3 1 1 . 4 4 11.50 3.76 1.60 --7.30 Day 7 --0.89 6.61 --1.72 Day 14 --16.29 --15.28 --7.57 --16.98 --9.71 Group 2 Day 0 Day 1 Day 3 Day 7 Day 14

--0.95 2.24 5.38 --0.21 --8.04

Animal 4 fibers Typell Typel

TypelI Typel

--1.04 --0.31 --1.24 4.84 4.35 8.09 5.55 11.68 3.75 3.73 9.00 --8.24 --1.27 --2.25 --3.23 --1.20 --12.71 --12.62 --5.44

--9.72 0.33 --8.23 --5.06 --6.47 3.15 --0.33 --3.34 0.21 --2.05 6.18 6.55 3.55 5.46 ~4.01 --7.76 --7.42 --12.34 --13.50 --12.86 --16.71 --12.13

Group 3 Day 0 --2.54 --5.96 Day 1 --4.05 --8.49 Day 3 6.54 --1.66 Day 7 6.76--10.95 Day 14 --12.43 --3.37

--1.34 3.75 0.10 --9.52 --4.90

~ . 7 0 --35.45 --6.11 --0.84 --4.75 --13.81 0.95 4.33 --4.79 ~.79 --2.54 --3.25 ~ . 2 7 --11.05 --14.33

Group 4 Day 0 Day 1 Day 3 Day 7 Day 14

0.65 2.87 0.19 --3.29 --7.59

0.10 0.90 1.93 9.58 --3.37 1.16 --9.63 2.51 --6.32 --13.01

2.46 --5.15 --5.92 --2.59 --1.21 --4.85 --8.53 --6.22 --8.31 --14.90

Animal 5 fibers

--3.37 5.00 --3.04 ~4.26 --15.16

--1.25 3.51 6.18 --3.79

Typell

0.22 5.20 8.30 --8.45

--4.14 1.42

4.17 --2.11 --7.53

1.01 --1.62 --2.15 --6.79 --8.23

--1.47

--5.49

--5.65 --6.18 --5.26

Fig. 5. Comparison of distribution of succinic dehydrogenase activity 7 days after tenotomy in randomly reinnervated soleus muscles. A : randomly reinnervated soleus muscle after transsection and reunion of the muscular branch of tibial nerve. Fiber type grouping is seen. All Type I fibers show abnormal distribution of succinic dehydrogenase activity and correspond to target fibers. Type II fibers do not show any abnormalities. B: randomly reinnervated soleus muscle after t ranssection and reunion of the sciatic nerve, regular distribution of succinic dehydrogenase activity both in Type 1 and Type II fibers is observed, x 63.

48 single muscle fibers showed a slight decrease of succinic dehydrogenase activity but these changes were n o t observed in all of the muscles examined. The picture of Type ! fibers of b o t h r a n d o m l y reinnervated muscles (from groups 3 a n d 4) is shown in Figs. 5A a n d B.

Morphometric observation I n the g r o u p o f a n i m a l s with n o r m a l t e n o t o m i z e d soleus muscle the mean muscle

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Fig. 6. Mean weights of soleus muscles at different timeintervalsafter tenotomy, expressed in percentage of control values from contralateral muscles. 0------@ tenotomized normal muscles ~ 0 u p 1); (3--.--.--(3 self-reinnervated and then tenotomized muscles (group 2); []--..--..--IS] randomly reinnervated muscles after transsection and reunion of the muscular branch of tibia/nerve and then tenotomized (group 3); I I . . . . . . ~ randomly reirmervated muscles after t r ~ t i o n and reunion of the sciatic nerve and then tenotomized (group 4), The outset values (day 0) for groups 2, 3, and 4 represent mean weights of reinnervated but not tenotomized soleus muscles. TABLE 2 THE MANN-WHITNEY TEST VALUES WHICH REPRESENT THE EVOLUTION OF NORMAL SOLEUS MUSCLE AFTER TENOTOMY Days

Muscle weight Type I fibers area Type II fibers area

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Fig. 7. The mean cross-sectional areas of Type I fibers in rat soleus muscles at different time intervals after tenotomy, expressed as a percentage of control value from contralateral leg. • • tenotomized normal muscles (group 1); ( 3 - - . - - ( 3 self-reinnervated, tenotomized muscles (group 2); [D--..--..--[~ randomly reinnervated muscles after transsection and reunion of the muscular branch of tibial nerve and then tenotomized (group 3) ; • . . . . . . • randomly reinnervated muscles after transsection and reunion of the sciatic nerve and then tenotomized (group 4). The outset values (day 0) for groups 2, 3 and 4 represent mean cross-sectional areas of Type I fibers from reinnervated but not tenotomized soleus muscles.

TABLE 3 THE M A N N - W H I T N E Y TEST VALUES W H I C H REPRESENT A COMPARISON BETWEEN TENOTOMIZED N O R M A L A N D TENOTOMIZED REINNERVATED SOLEUS MUSCLE Day 0

Day 1

Groups 1-2 Muscle weight Type I fibers Type II fibers

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Groups 1-3 Muscle weight Type I fibers Type II fibers

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Gro ups 1-4 Muscle weight Type I fibers Type II fibers

14 2 8

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Day 3

8 5

Day 7

Day 14

10 7

8 3

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22 2a 0a

12 9 3a

18 11 7

12 9 2

11 8 9

0a 0a 0a

a Significant at 95 ~ confidence limits (0.05 level).

50 weight increased by about 34 % one day after tenotomy and fell to 30 ~'/~}of the control after 7 days (Fig. 6, Table 2). The weight of reinnervated tenotomized muscles changed in the same way (Fig. 6, Table 3). The decrease is slower only in muscles which before tenotomy were self-reinnervated or randomly reinnervated after transsection and reunion of the muscular branch of the tibial nerve. In normal tenotomized muscles the size of the two types of fibers increased significantly just after tenotomy and then decreased (Tables 1 and 2, Figs. 7 and 8). Variations in Type I fibers were widest - - within the range from 150 % to 65 %, of contralateral control value. The differences of behaviour of Type I fibers between normal and reinnervated muscles after tenotomy are only observed in the first 3 days (Table 3, Fig. 7). The evolution of the cross-sectional area of Type II fibers after tenotomy is quite different in the 4 groups (Fig. 8). The observed decrease between the 3rd and 14th days after tenotomy is much slower in randomly reinnervated muscles than in normal and self-reinnervated ones. The degree of change is quite variable among rats of the same group and killed at identical times after tenotomy. For example, as regards Type I from day 1, rat 2 from group 3 had a percentage of 122.9 (t = +3.7), whereas rat 3 had 81.0% (t =: - - 4 . 7 ) (Table 1). Individual variations are also observed in the areas of muscle fibers of control animals.

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Fig. 8. The mean cross-sectional areas of Type II fibers in rat soleus muscles at different time intervals after tenotomy, expressed as a percentage of control value from contralateral leg. 0 ' -Q tenotomized normal muscles (group 1); O--.--O self-reinnervated, tenotomized muscles (group 2); U3--.. --[] randomly reinnervated muscles after transseetion and reunion of the muscular branch of tibial nerve and then tenotomized (group 3 ) ; j . . . . . . Brandomly re,innervated muscles after t r a n ~ o n and reunion of the sciatic nerve and then tenotomized (group 4). The outset values (day 0) for groups 2, 3 and 4 represent mean cross-sectional areas of Type II fibers from reinnervated but not tenotomized soleus muscles.

51 DISCUSSION Estimation of the composition of muscle fibers according to the percentage of the two basic enzymatic types confirmed our earlier observation that in muscle reinnervated withits own nerve a drastic decrease occurs of the percentage of Type II fibers and that the increase of the percentage of these fibers occurring in randomly reinnervated muscles depends on the distance from the muscle of the site of injury to the nerve. The results were not influenced by tenotomy performed 1 day earlier, since no evidence of conversion of Type I to Type II was demonstrated histochemically in tenotomized muscle (Engel et al. 1966; Tomanek and Cooper 1977). This allowed the influence of changes in the proportion of Type I and Type II fibers on the behaviour of the reinnervated soleus muscle after tenotomy to be followed. Structural and enzymatic changes produced by tenotomy in normal muscle were generally similar to those described by other authors, although most descriptions are concerned with the period beginning on the 5th day after tenotomy (Shafiq et al. 1969; Tomanek and Cooper 1972). An important observation seems to be that distinct changes appear as early as 1 day after tenotomy and are connected with the increase of the weight of the muscle, and also in the cross-sectional area of the muscle fibers. This may have been passive, due to shortening or may have been due to oedema. Reinnervation by itself changes the histochemical mosaic pattern of fibers and evokes grouping of fibers uniform as regards their histochemical characteristic (Yellin 1967). However, the histological picture of the particular muscle fiber does not differ from that of normal intact muscle. Structural and enzymatic abnormalities, i.e. target fibers, coil fibers, usually produced by tenotomy, were never observed in our experiments in reinnervated soleus muscles. Self-reinnervation as well as random reinnervation affects the behaviour of the soleus after tenotomy and this is manifested by a different degree of enzymatic and structural abnormalities and different evolution of the mean cross-sectional area of Type II fibers. Evolution of muscle weight and cross-sectional area of Type I fibers is essentially similar. The increase in Type II fibers to above 30 ~ in the reinnervated muscle after transsection and reunion of the muscular branch of the tibial nerve and to about 70 in reinnervated muscle after transsection and resuturing of the sciatic nerve was not associated with any visible changes in the reaction of Type II fibers to tenotomy. These fibers behave like those in normal tenotomized muscle in showing no distinctive structural and enzymatic abnormalities. The diminution of cross-sectional areas of Type II fibers in randomly reinnervated muscles occurs more slowly than in tenotomized normal and self-reinnervated muscles. The increase of the percentage of Type II fibers in randomly reinnervated muscles is probably the result of "foreign" nerve influence on the synthesis of myosin ATPase of another form in Type I fibers, involving cytoenzymatic conversion of Type I fibers to Type II (B~r/my and Close 1971 ; Brooke et al. 1971 ; Weeds et al. 1974). The conversion is associated with simultaneous changes in the sensitivity of the fibers to tenotomy. This seems to suggest that the relative sensitivity of fibers to tenotomy is a trait induced

52 by the influence of the neurone. Of course, this conclusion would be correct only if Type II fibers could arise in the reinnervation process, owing to transformation of Type 1 fibers, and not by myoblast proliferation (Hess and Rosner 1970) and substitution of Type I by Type II fibers by way of myogenesis. This possibility cannot be ruled out completely. However, denervation and associated atrophy of fibers and myoblast proliferation (Riley 1974) do not seem to be a necessary condition for cytoenzymatic fiber transformation. Effects similar to those obtained in the case ofcross-reinnervation and random reinnervation, such as cytoenzymatic transformation of fibers have been induced, for instance, by electrical stimulation of the muscle with stimuli of definite frequency (Salmons and Sreter 1976). Especially interesting is the fact that changes in the proportion of Type I and Type ]I fibers in reinnervated muscles are connected with changes in the behaviour of Type ! fibers after tenotomy. In self-reinnervated muscle, that is in a situation when a drastic decrease of the percentage of Type II fibers down to 0.4 ~ occurs, Type I fibers seem more sensitive and enzymatic and structural changes more pronounced than in normal tenotomized muscle. The increase in Type II fibers to above 30 ~ in randomly reinnervated muscle after transsection and reunion of the muscular branch of the tibial nerve did not cause any visible differences in the reaction of Type I fibers to tenotomy as compared to the reaction of Type I fibers in normal tenotomized muscle. However, when the increase in Type II fibers reached a value about 70 ~, Type I fibers become much less sensitive than in normal tenotomized muscle. The only symptoms of atrophy that were observed consisted in a diminution of the cross-sectional area of the fibers, showing no noticeable structural abnormalities and changes in enzymatic activity. Thus, Type I fibers in the soleus muscle with muscle fiber type composition after reinnervation similar to that of the "white" type (Henneman and Olson 1965), behave like those of "white" muscle after tenotomy (McMinn and Vrbov/t 1964). The reason for the lower sensitivity to tenotomy of Type I fibers in "white" type of muscle is unknown. It seems that at least one condition may be the different pattern of activation of the "white" muscle (Eccles et al. 1958). Tenotomy immediately reduces the electromyographic activity of the "red" soleus muscle, without affecting at this time the activation of the "white" tibialis anterior (Vrbov~ 1963). On the other hand, it was established that electrical stimulation of the tenotomized soleus retards the atrophic processes occurring in it (McMinn and Vrbov/t 1967). If the soleus muscle is reinnervated by neurones which in normal conditions innervated "white" muscles it gains a large number of "fast" motor units (Kugelberg 1976), and the pattern of activation and use of such a muscle must change (Close 1965; Romanul and Van der Meulen 1967; Crockett and Edgerton 1975). If the activity of such a muscle becomes similar to that of"white" one, this might significantly change the sensitivity of its muscle fibers to tenotomy. The direct influence of the neurone on the single muscle fiber, conditioning its cytoenzymatic character, does not seem, therefore, to be the only factor controlling the degree of sensitivity to tenotomy. An important role seems to be played here by the proportion of the fiber types, that is proportion of "fast" to "stow" motor units, hence the pattern of impulse and utilization of randomly reinnervated muscle.

53 REFERENCES B~.r~iny, M. and R. J. Close (1971) The transformation of myosin in cross-innervated rat muscle, J. Physiol. (Lond.), 213 : 455-474. Brooke, M. H. and K. K. Kaiser (1970) Muscle fiber types - - How many and what kind?, Arch. NeuroL (Chic.), 23: 369-379. Brooke, M. H., E. Williamson and K. K. Kaiser (1971) The behaviour of four fiber types in developing and reinnervated muscle, Arch. Neurol. (Chic.), 25: 360-366. Close, R. (1965) Effect of cross union of motor nerves to fast and slow skeletal muscles, Nature (Lond.), 206: 831-832. Crockett, J. L. and V. R. Edgerton (1975) Exercise and restricted activity effects on reinnervated and cross-innervated skeletal muscles, J. neurol. Sci., 25: 1-9. Eccles, J. C. (1944) Investigations on muscle atrophies arising from disuse and tenotomy, J. Physiol. (Lond.), 103 : 253-266. Eccles, J. C., R. M. Eccles and A. Lundberg (1958) The action potentials of the alpha motoneurones supplying fast and slow muscles, J. Physiol. (Lond.), 142: 275-291. Engel, W. K., M. H. Brooke and P. G. Nelson (1966) Histochemical studies of denervated or tenotomized cat muscle - - Illustrating difficulties in relating experimental animal conditions to human neuromuscular diseases, Ann. N. Y. Acad. Sci., 138: 160-185. Guth, L. and F. J. Samaha (1969) Qualitative differences between actomyosin ATPase of slow and fast mammalian muscle, Exp. Neurol., 25: 138-152. Guth, L. and F. J. Samaha (1970) Procedure tor the histochemical demonstration of actomyosin ATPase, Exp. Neurol., 28 : 365-367. Henneman, E. and C. B. Olson (1965) Relations between structure and function in the design of skeletal muscles, J. NeurophysioL, 28: 581-598. Hess, A. and S. Rosner (1970) The satellite cell bud and myoblasts in denervated mammalian muscle fibers, Amer. J. Anat., 129: 21-40. Jaffe, D. M., R. D. Terry and A. J. Spiro (1978) Disuse atrophy of skeletal muscle - - A morphometric study using image analysis, J. neurol. Sci., 35: 189-200. Karpati, G. and W. K. Engel (1967) Neuronal trophic function - - a new aspect demonstrated histochemically in developing soleus muscle, Arch. Neurol. (Chic.), 17: 542-545. Kugelberg, E. (1976) Adaptive transformation of rat soleus motor units during growth - - Histochemistry and contraction speed, J. neurol. Sci., 27: 269-289. Liley, A. W. (1956) An investigation of spontaneous activity at the neuromuscular junction of the rat, J. Physiol. (Lond.), 132: 650-666. McMinn, R. M. H. and G. Vrbov~ (1962) Morphological changes in red and pale muscles following tenotomy, Nature (Lond.), 195: 509. McMinn, R. M. H. and G. Vrbov~i (1964) The effect of tenotomy on the structure of fast and slow muscle in the rabbit, Quart. J. exp. Physiol., 49: 424-429. McMinn, R. M. H. and G. Vrbov~i (1967) Motor neurone activity as a cause of degeneration in the soleus muscle of the rabbit, Quart. J. exp. PhysioL, 52:41 l~-I 5. Mommaerts, W. F. H. M., K. Seraydarian, Miwon Suh, C. J. C. Kean and A. J. Buller (1977) The conversion of some biochemical properties of mammalian skeletal muscles following crossreinnervation, Exp. Neurol., 55 : 637-653. Nachlas, M. M., K. C. Tsou, E. DeSousa, C. S. Cheng and A. M. Seligman (1957) Cytochemical demonstration of succinic dehydrogenase by the use of new p-nitrophenyl substituted ditetrazole, J. Histochem, Cytochem., 5 : 420-436. Nelson, P. G. (1969) Functional consequences of tenotomy in hind limb muscles of the cat, J. Physiol. (Lond.), 201 : 321-333. Pullen, A. H. (1977) The distribution and relative sizes of fibre types in the extensor digitorum longus and soleus muscles of the adult rat, J. Anat. (Lond.), 123 : 467-486. Riley, D. A. (1974) Factors affecting the conversion of cross-reinnervated skeletal muscle, Amer. J. Anat., 140: 609-615. Romanul, F. C. A. and J. P. Van der Meulen (1967) Slow and fast muscles after cross-innervation, Arch. Neurol. (Chic.), 17: 387-402. Rymaszewska-Kossakowska, T. and A. ~liwowski (1977) Histochemical composition of " r e d " and "white" skeletal muscles reinnervated through a preserved allogeneic peripheral nerve graft, Acta. med.pol., 18: 85-96.

54 Salmons, S. and F. A. Sr6ter (1976) Significance of impulse activity in the transformation of skeletal muscle type, Nature (Lond.), 263 : 30 34. Samaha, F. J., L. G u t h and R. W. Albers (1970) The neural regulation of gene expression in the muscle cell, Exp. Neurol., 27: 276-282. Scott, K. W. M. and J. Hoy (1976) The cross sectional area of diaphragmatic muscle fibers in emphysema, measured by an automated image analysis system, I. P~th., 120:121-128. Shafiq, S. A., M. A. Gorycki, S. A. Asiedu and A. T. Milhorat (1969) Tenotomy - - Effect on the fine structure of the soleus of the rat, Arch. Neurol. (Chic.), 20: 625-633. Tomanek, R. J. and R. R. Cooper (1972) Ultrastructural changes in tenotomized fast and slow-twitch muscle fibres, J. Anat. (Lond.), 113 : 40%424. Vrbov/i, G. (1963) Changes in the motor reflexes produced by tenotomy, J. Physiol. (Lond.), 166: 241-250. Weeds, A. A., D. R. Trentham, C. J. C. Kean and A. J. Buller (1974) Myosin from cross-reinnervated cat muscles, Nature (Lond.), 247: 135-139. Yellin, H. (1967) Neural regulation of enzymes in muscle fibers of red and white muscle, Exp. Neurol.. 19" 92-103.

Effect of tenotomy on self-reinnervated and randomly reinnervated soleus muscle of rat.

Journal of the Neurological Sciences, 1979, 41 : 39-54 © Elsevier/North-Holland Biomedical Press 39 E F F E C T OF T E N O T O M Y O N S E L F - R E...
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