Article Figures & Tables
Figures
- Fig. 1.
Example of isometric twitch contractions at 21°C of soleus (A) and extensor digitorum longus (B) muscle of Suncus etruscus stimulated simultaneously with a supramaximal electrical pulse of 1 ms duration. The curves are digital scans of original recordings. Time to peak force (tp) is the time between the stimulus (upward-pointing arrow) and the occurrence of maximal force, and the 50, 75 and 90% relaxation times (tr50, tr75, tr90) are the times for the decay from maximal force to 50, 25 and 10% of maximal force, respectively.
- Fig. 2.
Myosin heavy chain composition of extensor digitorum longus (EDL) (17 pooled muscles) and soleus (SOL) (16 pooled muscles) of Suncus etruscus demonstrated by electrophoresis. Lane M, myosin heavy chains HCI and HCIId of rabbit muscles.
- Fig. 3.
Myosin light chain composition (fLC1 and fLC2) of extensor digitorum longus (A) and soleus (B) muscle of Suncus etruscus separated by two-dimensional electrophoresis. TM, tropomyosin.
- Fig. 4.
Ratio of lactate dehydrogenase to citrate synthase (LDH/CS) activity in gastrocnemius muscle of mammals of different body masses (Mb). The symbols represent data for Suncus etruscus (▪) and Crocidura russula (▴) (Peters et al., 1999) together with those for the shrew Sorex vagrans (body mass 4-5 g) ([UNK]) and several larger mammals (○), taken from Emmett and Hochachka (1981). The solid line is the result of a linear regression on a double-logarithmic scale in which all data points were included: log(LDH/CS)=0.304logMb+0.623; r2=0.62).
- Fig. 5.
Pattern of electrophoretically separated cytosolic proteins and corresponding densitograms of extensor digitorum longus (EDL) (17 pooled muscles) and soleus (SOL) (16 pooled muscles) of Suncus etruscus. CK, creatine kinase.
Tables
- Table 1.
Characteristics of isometric twitch contractions of the extensor digitorum longus and the soleus muscles of Suncus etruscus (body mass 2.2±0.3 g, N=12) at 25°C
Muscle Muscle mass (mg) tp (ms) tr50 (ms) tr75 (ms) tr90 (ms) Soleus (N=5) 0.37±0.04 12.7±2.3 17.3±4.6 27.7±6.5 42.2±10.8 EDL (N=6) 0.45±0.08 11.0±1.1 11.6±2.6* 16.7±2.9** 27.0±3.8** -
Values are means ± S.D. for N muscles.
tp, time to peak force; tr50, tr75, tr90, 50, 75 and 90% relaxation times.
Significance levels are calculated for the difference between extensor digitorum longus (EDL) and soleus muscle: *P<0.05, **P<0.01 (unpaired t-test).
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- Table 2.
Characteristics of force and Ca2+ transients of fibre bundles of the extensor digitorum longus and the soleus muscles of Suncus etruscus at 25°C
Signal Muscle tp (ms) tr50 (ms) tr75 (ms) Force of muscle fibre bundle Soleus (N=27) 13.2±1.5 17.6±2.3 30.0±3.7 EDL (N=9) 10.6±0.9** 9.3±1.7** 12.6±1.9** Ca2+ transient Soleus (N=19) 9.5±3.2 21.8±9.2 37.4±13.3 EDL (N=6) 5.3±2.4** 16.1±4.9* 23.7±4.1** -
Values are means ± S.D. for N measurements per muscle bundle.
tp, time to peak force; tr50, tr75, 50 and 75% relaxation times.
Significance levels are calculated for the difference between extensor digitorum longus (EDL) and soleus: *P<0.05, **P<0.01 (unpaired t-test).
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- Table 3.
Time to peak force of isometric extensor digitorum longus and soleus twitches and the fibre composition of the two muscles in mammals of different size at 25°C
EDL Soleus Species Mean body mass (g) tp (ms) Fast-twitch/slow-twitch fibres (%) tp (ms) Fast-twitch/slow-twitch fibres (%) Reference Suncus etruscus 2.2 11 100/0 13 100/0 This study Crocidura russula 8.6 14 100/0 18 100/0 This study White mouse 35 14 100/0 41 54/46 Asmussen and Gaunitz (1989) Young Wistar rat 120 20 95/5 48 30/70 Asmussen and Gaunitz (1989) Wistar rat 200 27* 97/3 80* 0/100 Geers and Gros (1990) Guinea pig 350 20 94/6 94 0/100 Asmussen and Gaunitz (1989) -
EDL, extensor digitorum longus.
tp, time to peak force; *converted from 20.5 to 25°C using Q10 values obtained from Asmussen and Gaunitz (1989).
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- Table 4.
Fibre composition of the extensor digitorum longus and soleus muscles of some shrew species
Fibre types, I/IIA/IIB/IID (%) Shrew species Body mass (g) EDL Soleus Suncus etruscus 2.2 0 / 0 / 0 / 100 0 / 0 / 0 / 100 Sorex araneus * 7-10 — 0 / 0 / 2 / 98 Crocidura russula 8.4 0 / 0 / 58 / 42 0 / 0 / 54 / 46 Suncus murinus † 20-60 — 0 / 93 / 7 / 0 -
EDL, extensor digitorum longus.
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↵ * Data from Savolainen and Vornanen (1995); †data from Suzuki (1990).
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- Table 5.
Specific activities of lactate dehydrogenase and citrate synthase in the extensor digitorum longus, soleus and gastrocnemius muscles of Suncus etruscus
Muscle Specific activity LDH/cpr (mmol min-1 mg-1) Specific activity CS/cpr (mmol min-1 mg-1) LDH/CS activity ratio EDL (N=17) 1.31 0.94 1.4 Soleus (N=16) 1.14 0.84 1.4 Gastrocnemius (N=4) 1.49 1.28 1.2 -
cpr, cytoplasmic protein concentration given in mg ml-1; N is the number of pooled muscles.
LDH, lactate dehydrogenase; CS, citrate synthase; EDL, extensor digitorum longus.
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