+ Site Statistics
+ Resolve Accession
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
Submit PDF Full TextSubmit PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Electrophysiological properties of neonatal rat motoneurons studies in vitro

, : Electrophysiological properties of neonatal rat motoneurons studies in vitro. Journal of Physiology (Cambridge) 370: 651-680

The electroresponsive properties of neonatal lumbar spinal motoneurones were studied using isolated, hemisected spinal cords from neonatal rats aged 3-12 days. The extracellular and intracellular responses to electrical stimulation of the ventral and dorsal root were studied as well as the intracellular response to current injection. Field potentials recorded in the lateral motor area following electrical stimulation of lumbar ventral roots had a triphasic positive-negative-positive wave form. The negative component did not return to the base line smoothly but exhibited a 'shoulder' where the negativity increased in duration. Following electrical stimulation of the dorsal root, presynaptic field potentials were recorded upon activation of the afferent axons as well as following synaptic activation of interneurones and motoneurones. The input resistances of neonatal motoneurones determined from the slope of current-voltage plots were high compared wih the adult. The resistance decreased with age with a mean of 18.1 M.OMEGA. for animals 3-5 days old 8.8 M.OMEGA. for animals 6-8 days old and 5.4 M.OMEGA. for animals 9-11 days old. Values for the membrane time constant were similar to those in the adult with a mean of 4.5 ms. Action potentials elicited by ventral or dorsal root stimulation or by intracellular current injection were marked by a pronounced after-depolarization (a.d.p.) and an after-hyperpolarization (a.h.p.). The amplitude of the a.h.p. varied with that of the a.d.p. The amplitude of excitatory post-synaptic potentials (e.p.s.p.s) elicited by electrical stimulation of the dorsal root was affected by intracellular current injection. Two types of e.p.s.p.s were distinguished: those with a biphasic reversal (early phase first) and those in which the early phase was unaffected by inward current injection while the later phase was reversed. Unlike in the adult, the reversals could be achieved with low current levels and the amplitude of both types of e.p.s.p. was increased by inward current injection. Inhibitory post-synaptic potentials (i.p.s.p.s) were elicited by dorsal or ventral root stimulation. The amplitude of these i.p.s.p.s was diminished and reversed in sign with inward current injection and their amplitude was enhanced with outward current injection. Activation of neonatal motoneurones with long current pulses revealed that there is one steady-state firing range. The firing properties of neonatal motoneurones differ from those of adult rat in that (a) there is no clear threshold for repetitive firing, (b)there is a low maximum firing frequency (near 30 Hz) and (c)the slope of the firing frequency-injected current (f-I) plot has a high gain. These results are discussed with respect to previous findings in adult rat and eat and with reference to the properties of the developing nervous and muscular systems.

(PDF 0-2 workdays service)

Order PDF Full Text


Click here to order any other PDF Full Text

Accession: 005349738

PDF Full Text: Submit

Submit PDF Full Text

No spam - Every submission is manually reviewed

Due to poor quality, we do not accept files from Researchgate

Submitted PDF Full Texts will always be free for everyone
(We only charge for PDFs that we need to acquire)

Select a PDF file:

Other references

Bigelow, M. W.; Kleinman, J. G.; Wiessner, J. H.; Mandel, N. S., 1995: Crystal attachment to inner medullary collecting duct cells Effect of membrane composition and structure. Journal of the American Society of Nephrology 6(3): 944

Ivanova L.V.; Voronin V.M.; Pekarskii M.I., 1969: Bone marrow changes in patients with typhoid fever and chronic bacteria carriers. Sovetskaya Meditsina 32(6): 75-79

Yao JinZhong; Niu ZuiRong; Huang WeiDong, 2005: Study on the optimized redistribution of water resources by the water-transferring project from the Datong River to the Qinwangchuan Irrigated Area. The water transferring project from the Datong River to the Qinwangchuan Irrigated Area, Yongdeng County, Lanzhou City, is located in the central part of Gansu Province, China, and the climate is arid. The construction of the project was started f...

Crosby, T. F.; Morris, D. J., 1986: Synovex-S and Finaplix in early lamb production. An efficacy study using 3 pellets of Synovex-S (each pellet containing 2.5 mg oestradiol benzoate + 25 mg progesterone) implanted alone or in combination with 4 pellets of Finaplix (each pellet containing 20 mg of trenbolone acetate) was carried o...

Schroder, C., 1904: Eine Sammlung von Referaten uber neuere biometrische Arbeiten, mit einzelnen Anmerkungen. Allgemeine Zeitschrift fuer Entomologie, IX 228-246

Urbanek, H.; Yirdaw, G., 1978: Acid proteases produced by fusarium spp in cultures and in infected seedlings. Protease secretion was found when F. culmorum, F. avenaceum and F. oxysporum were grown in a mineral-protein medium, a cell wall medium and during infection of maize seedlings. Proteases from fungal cultures on mineral-protein medium were partiall...

W. Von Tümpling; N. Scheibe; J. W. Einax, 2013: Extended Sediment Quality Rating for Trace Elements in Urban Waters – Case Study Klinke, Germany. The European Water Framework Directive (WFD) commits European Union member states to achieving good ecological status in all water bodies by 2015. For sediments the definition of good chemical status is based on numerical sediment quality guidelin...

Fassbinder W., 1988: Results and course of disease following kidney transplant. Versicherungsmedizin 40(5): 129-131

Holechek, Jl, 1992: Financial benefits of range management practices in the Chihuahan desert. Rangelands 14(5): 279-284

Hinterdorfer, P.; Schilcher, K.; Gruber, H. J.; Baumgartner, W.; Schindler, H., 1997: Detection of recognition events on biological samples with force microscopy. Biophysical Journal 72(2 PART 2): A212