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Volume 1, Issue 3 (Summer 1997)                   J Arak Uni Med Sci 1997, 1(3): 8-12 | Back to browse issues page

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Jamshidi Fard A, Bagust J. Spreeding And Conduction Velocities of Primary Afferent Fibres Studies on Isolated (In Vitro) Mammalian Spinal Cord. J Arak Uni Med Sci. 1997; 1 (3) :8-12
URL: http://jams.arakmu.ac.ir/article-1-6525-en.html
1- Arak University of Medical Sciences, Arak, Iran.
2- School of Medicine, University of Southampton, UK.
Abstract:   (228 Views)
Wall  and  Shortland (1991) have  shown  that  afferent  fibres  entering  the  cord  in  thoracic  and  lumbar  roots  of  adult  rats  have  branches  that  may  penetrate  up  to  11  segments  caudally  from  the  root  entry  zone.  We  have  investigated  the  extent  of  branching  and  conduction  velocities  of  ascending  and  descending  branches  of  lumbar  and  thoracic  primary  afferent  in  isolated  spinal  cords  of  adults  hamsters  (60-100g) and  juvenile  rats  (30-46 g). Hemisected  spinal  cords  were  maintained  at  cold  artificial  cerebrospinal  fluid (25-27 C) in  which  the  Ca2+  had  been  replaced  by  Mn2+ (2mm) to  block  synaptic  activity. Hamsters, antidromic  conducted  responses  were  obtained  up  to  10  segments  caudal  to  dorsal  roots T6-T7   and  17  segments  rostral  to L3. The  mean  conduction  velocity  was  3.7 m/s  (s.e.m.& 0.4)  for  descending  primary  afferents(n=21) and  9.9 a 1.2 m/s for  ascending  afferents (n=26). In the  rat , antidromic  responses  were  measured  over  4 segments  caudal  and  17  segments  rostral  to  the  L3 dorsal  root. Conclusion  velocities  were  4.4  & 0.5  m/s  and  7.7  &  0.7  m/s  for  descending  and  ascending  branches  respectively (n=4). The  result  were  similar  to  those  reported  by  Wall  &  Shortland , although  the  temperature. Difference  between  the  in  vitro  and  in  vivo  preparations  would  have  resulted  in  approximately  halving  of  the  velocity  in  isolated  cord  preparation.  The  conduction  velocity  of  descending  fibres  was  about  half  fibres  which  may  be  related  to  size  differences  within  the  branches.
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Type of Study: Review Article | Subject: Internal
Accepted: 1997/06/22

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