Abstract
1. Isometric contractile characteristics of fast-twitch (flexor digitorum longus, FDL; medial gastrocnemius, MG) and slow-twitch (soleus) muscles were determined in pentobarbitone-anaesthetized fetal sheep between 90 and 140 days gestation. Five fetuses were hypophysectomized (HPX) at 90-95 days gestation and then studied at 138-140 days. 2. At 90-95 days gestation the time to peak of single twitch contractions for the soleus, MG and FDL were not significantly different from each other; the mean value (+/-S.E.M.) for all the muscles at this age was 77.6 +/- 9.0 ms. At 120-125 days gestation the MG and FDL contracted significantly faster (44.0 +/- 0.9 and 40.8 +/- 1.8 ms, respectively) than at 90-95 days, and did not change significantly thereafter. In contrast, the soleus muscle contracted more slowly (111.9 +/- 6.6 ms) at 138-140 days than at 90-95 days and 120-125 days gestation. 3. Soleus muscle consisted of type I fibres at all gestational ages. There was no significant change with gestational age in the relative numbers of type I and II fibres in the MG and FDL, but in the diaphragm the number of type I fibres increased and the number of type II fibres decreased between 125 and 138 days gestation. 4. HPX abolished the normal increase of soleus weight relative to body weight between 125 and 138 days but did not alter the change of twitch contraction time with age. HPX significantly prolonged twitch time to peak and time to half-relaxation of MG and time to half-relaxation of FDL at 138 days. 5. The maximum rate of rise of the isometric tetanic contraction was unchanged by HPX in all three hindlimb muscles, but fatigue of MG and FDL was increased. 6. The relative proportions of different fibre types in the hindlimb muscles and the diaphragm were unchanged by HPX, but there was a significant decrease in mean areas of type I and II fibres in the FDL and MG of the HPX fetuses.
Full text
PDF










Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Allen R. E., Boxhorn L. K. Regulation of skeletal muscle satellite cell proliferation and differentiation by transforming growth factor-beta, insulin-like growth factor I, and fibroblast growth factor. J Cell Physiol. 1989 Feb;138(2):311–315. doi: 10.1002/jcp.1041380213. [DOI] [PubMed] [Google Scholar]
- Andrianakis P., Walker D. W., Ralph M. M., Thorburn G. D. Effect of inhibiting prostaglandin synthesis in pregnant sheep with 4-aminoantipyrine under normothermic and hyperthermic conditions. Am J Obstet Gynecol. 1989 Jul;161(1):241–247. doi: 10.1016/0002-9378(89)90273-1. [DOI] [PubMed] [Google Scholar]
- BULLER A. J., ECCLES J. C., ECCLES R. M. Interactions between motoneurones and muscles in respect of the characteristic speeds of their responses. J Physiol. 1960 Feb;150:417–439. doi: 10.1113/jphysiol.1960.sp006395. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baldwin K. M., Hooker A. M., Campbell P. J., Lewis R. E. Enzyme changes in neonatal skeletal muscle: effect of thyroid deficiency. Am J Physiol. 1978 Sep;235(3):C97–102. doi: 10.1152/ajpcell.1978.235.3.C97. [DOI] [PubMed] [Google Scholar]
- Bhakthavathsalan A., Mann L. I., Ayromlooi J., Kunzel W., Liu M. The effects of fetal thyroidectomy in the ovine fetus. Am J Obstet Gynecol. 1977 Feb 1;127(3):278–284. doi: 10.1016/0002-9378(77)90469-0. [DOI] [PubMed] [Google Scholar]
- Burke R. E., Levine D. N., Zajac F. E., 3rd Mammalian motor units: physiological-histochemical correlation in three types in cat gastrocnemius. Science. 1971 Nov 12;174(4010):709–712. doi: 10.1126/science.174.4010.709. [DOI] [PubMed] [Google Scholar]
- Clewlow F., Dawes G. S., Johnston B. M., Walker D. W. Changes in breathing, electrocortical and muscle activity in unanaesthetized fetal lambs with age. J Physiol. 1983 Aug;341:463–476. doi: 10.1113/jphysiol.1983.sp014817. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cooke I. R., Berger P. J. Precursor of respiratory pattern in the early gestation mammalian fetus. Brain Res. 1990 Jul 9;522(2):333–336. doi: 10.1016/0006-8993(90)91479-z. [DOI] [PubMed] [Google Scholar]
- Czerwinski S. M., Martin J. M., Bechtel P. J. Modulation of IGF mRNA abundance during stretch-induced skeletal muscle hypertrophy and regression. J Appl Physiol (1985) 1994 May;76(5):2026–2030. doi: 10.1152/jappl.1994.76.5.2026. [DOI] [PubMed] [Google Scholar]
- Dawes G. S., Fox H. E., Leduc B. M., Liggins G. C., Richards R. T. Respiratory movements and rapid eye movement sleep in the foetal lamb. J Physiol. 1972 Jan;220(1):119–143. doi: 10.1113/jphysiol.1972.sp009698. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Deayton J. M., Young I. R., Thorburn G. D. Early hypophysectomy of sheep fetuses: effects on growth, placental steroidogenesis and prostaglandin production. J Reprod Fertil. 1993 Mar;97(2):513–520. doi: 10.1530/jrf.0.0970513. [DOI] [PubMed] [Google Scholar]
- Finkelstein D. I., Andrianakis P., Luff A. R., Walker D. W. Developmental changes in hindlimb muscles and diaphragm of sheep. Am J Physiol. 1992 Oct;263(4 Pt 2):R900–R908. doi: 10.1152/ajpregu.1992.263.4.R900. [DOI] [PubMed] [Google Scholar]
- Finkelstein D. I., Andrianakis P., Luff A. R., Walker D. Effects of thyroidectomy on development of skeletal muscle in fetal sheep. Am J Physiol. 1991 Nov;261(5 Pt 2):R1300–R1306. doi: 10.1152/ajpregu.1991.261.5.R1300. [DOI] [PubMed] [Google Scholar]
- Guth L., Samaha F. J. Procedure for the histochemical demonstration of actomyosin ATPase. Exp Neurol. 1970 Aug;28(2):365–367. [PubMed] [Google Scholar]
- Harding R., Hooper S. B., Han V. K. Abolition of fetal breathing movements by spinal cord transection leads to reductions in fetal lung liquid volume, lung growth, and IGF-II gene expression. Pediatr Res. 1993 Aug;34(2):148–153. doi: 10.1203/00006450-199308000-00008. [DOI] [PubMed] [Google Scholar]
- Hausman G. J. Histochemical studies of muscle development in decapitated and hypophysectomized pig fetuses: blood vessel development. J Anim Sci. 1989 May;67(5):1367–1374. doi: 10.2527/jas1989.6751367x. [DOI] [PubMed] [Google Scholar]
- Hoh J. F. Myogenic regulation of mammalian skeletal muscle fibres. News Physiol Sci. 1991 Feb;6:1–6. doi: 10.1152/physiologyonline.1991.6.1.1. [DOI] [PubMed] [Google Scholar]
- Latimer A. M., Hausman G. J., McCusker R. H., Buonomo F. C. The effects of thyroxine on serum and tissue concentrations of insulin-like growth factors (IGF-I and -II) and IGF-binding proteins in the fetal pig. Endocrinology. 1993 Sep;133(3):1312–1319. doi: 10.1210/endo.133.3.7689951. [DOI] [PubMed] [Google Scholar]
- Luff A. R., Atwood H. L. Changes in the sarcoplasmic reticulum and transverse tubular system of fast and slow skeletal muscles of the mouse during postnatal development. J Cell Biol. 1971 Nov;51(21):369–383. doi: 10.1083/jcb.51.2.369. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Mesiano S., Young I. R., Baxter R. C., Hintz R. L., Browne C. A., Thorburn G. D. Effect of hypophysectomy with and without thyroxine replacement on growth and circulating concentrations of insulin-like growth factors I and II in the fetal lamb. Endocrinology. 1987 May;120(5):1821–1830. doi: 10.1210/endo-120-5-1821. [DOI] [PubMed] [Google Scholar]
- Mesiano S., Young I. R., Hey A. W., Browne C. A., Thorburn G. D. Hypophysectomy of the fetal lamb leads to a fall in the plasma concentration of insulin-like growth factor I (IGF-I), but not IGF-II. Endocrinology. 1989 Mar;124(3):1485–1491. doi: 10.1210/endo-124-3-1485. [DOI] [PubMed] [Google Scholar]
- Muller A., van Hardeveld C., Simonides W. S., van Rijn J. The elevation of sarcoplasmic reticulum Ca2(+)-ATPase levels by thyroid hormone in the L6 muscle cell line is potentiated by insulin-like growth factor-I. Biochem J. 1991 Apr 1;275(Pt 1):35–40. doi: 10.1042/bj2750035. [DOI] [PMC free article] [PubMed] [Google Scholar]
- NOVIKOFF A. B., SHIN W. Y., DRUCKER J. Mitochondrial localization of oxidative enzymes: staining results with two tetrazolium salts. J Biophys Biochem Cytol. 1961 Jan;9:47–61. doi: 10.1083/jcb.9.1.47. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nwoye L., Mommaerts W. F., Simpson D. R., Seraydarian K., Marusich M. Evidence for a direct action of thyroid hormone in specifying muscle properties. Am J Physiol. 1982 Mar;242(3):R401–R408. doi: 10.1152/ajpregu.1982.242.3.R401. [DOI] [PubMed] [Google Scholar]
- Peter J. B., Barnard R. J., Edgerton V. R., Gillespie C. A., Stempel K. E. Metabolic profiles of three fiber types of skeletal muscle in guinea pigs and rabbits. Biochemistry. 1972 Jul 4;11(14):2627–2633. doi: 10.1021/bi00764a013. [DOI] [PubMed] [Google Scholar]
- Pette D., Vrbová G. Neural control of phenotypic expression in mammalian muscle fibers. Muscle Nerve. 1985 Oct;8(8):676–689. doi: 10.1002/mus.880080810. [DOI] [PubMed] [Google Scholar]
- Ruckebusch Y., Gaujoux M., Eghbali B. Sleep cycles and kinesis in the foetal lamb. Electroencephalogr Clin Neurophysiol. 1977 Feb;42(2):226–237. doi: 10.1016/0013-4694(77)90029-3. [DOI] [PubMed] [Google Scholar]
- Rurak D. W., Gruber N. C. Increased oxygen consumption associated with breathing activity in fetal lambs. J Appl Physiol Respir Environ Exerc Physiol. 1983 Mar;54(3):701–707. doi: 10.1152/jappl.1983.54.3.701. [DOI] [PubMed] [Google Scholar]
- SCOW R. O. Effect of growth hormone and thyroxine on growth and chemical composition of muscle, bone and other tissues in thyroidectomized-hypophysectomized rats. Am J Physiol. 1959 Apr;196(4):859–865. doi: 10.1152/ajplegacy.1959.196.4.859. [DOI] [PubMed] [Google Scholar]
- Salmons S., Sréter F. A. Significance of impulse activity in the transformation of skeletal muscle type. Nature. 1976 Sep 2;263(5572):30–34. doi: 10.1038/263030a0. [DOI] [PubMed] [Google Scholar]
- Walker D. W., Schuijers J. A. Effect of thyroidectomy on cardiovascular responses to hypoxia and tyramine infusion in fetal sheep. J Dev Physiol. 1989 Dec;12(6):337–345. [PubMed] [Google Scholar]
- Wrutniak C., Cabello G., Bosc M. Plasma free and total iodothyronine levels in hypophysectomized and intact lamb foetuses during the last third of gestation. Acta Endocrinol (Copenh) 1985 Nov;110(3):388–394. doi: 10.1530/acta.0.1100388. [DOI] [PubMed] [Google Scholar]
