Phrenic motoneuron morphology during rapid diaphragm muscle growth

Y.s. Prakash, Carlos Bernardo Mantilla, Wen Z. Zhan, Kenneth G. Smithson, Gary C Sieck

Research output: Contribution to journalArticle

67 Citations (Scopus)

Abstract

In the adult rat, there is a general correspondence between the sizes of motoneurons, motor units, and muscle fibers that has particular functional importance in motor control. During early postnatal development, after the establishment of singular innervation, there is rapid growth of diaphragm muscle (Dia(m)) fibers. In the present study, the association between Dia(m) fiber growth and changes in phrenic motoneuron size (both somal and dendritic) was evaluated from postnatal day 21 (D21) to adulthood. Phrenic motoneurons were retrogradely labeled with fluorescent tetramethylrhodamine dextran (3,000 MW), and motoneuron somal volumes and surface areas were measured using three-dimensional confocal microscopy. In separate animals, phrenic motoneurons retrogradely labeled with choleratoxin B-fragment were visualized using immunocytochemistry, and dendritic arborization was analyzed by camera lucida. Between D21 and adulthood, Dia(m) fiber cross-sectional area increased by ~164% overall, with the growth of type II fibers being disproportionate to that of type I fibers. There was also substantial growth of phrenic motoneurons (~360% increase in total surface area), during this same period, that was primarily attributable to an expansion of dendritic surface area. Comparison of the distribution of phrenic motoneuron surface areas between D21 and adults suggests the establishment of a bimodal distribution that may have functional significance for motor unit recruitment in the adult rat.

Original languageEnglish (US)
Pages (from-to)563-572
Number of pages10
JournalJournal of Applied Physiology
Volume89
Issue number2
StatePublished - 2000

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Motor Neurons
Diaphragm
Muscles
Growth
Neurophysiological Recruitment
Neuronal Plasticity
Confocal Microscopy
Immunohistochemistry

Keywords

  • Cholera-toxin
  • Confocal microscopy
  • Immunocytochemistry
  • Rat motor unit
  • Recruitment

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Phrenic motoneuron morphology during rapid diaphragm muscle growth. / Prakash, Y.s.; Mantilla, Carlos Bernardo; Zhan, Wen Z.; Smithson, Kenneth G.; Sieck, Gary C.

In: Journal of Applied Physiology, Vol. 89, No. 2, 2000, p. 563-572.

Research output: Contribution to journalArticle

Prakash, Y.s. ; Mantilla, Carlos Bernardo ; Zhan, Wen Z. ; Smithson, Kenneth G. ; Sieck, Gary C. / Phrenic motoneuron morphology during rapid diaphragm muscle growth. In: Journal of Applied Physiology. 2000 ; Vol. 89, No. 2. pp. 563-572.
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