| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Departments of 1 Physiology and 2 Pharmacology, University of Alberta, Edmonton, Alberta, Canada T6G 2S2
The following two hypotheses regarding diaphragm contractile properties in the perinatal rat were tested. First, there is a major transformation of contractile and fatigue properties during the period between the inception of inspiratory drive transmission in utero and birth. Second, the diaphragm muscle properties develop to functionally match changes occurring in phrenic motoneuron electrophysiological properties. Muscle force recordings and intracellular recordings of end-plate potentials were measured by using phrenic nerve-diaphragm muscle in vitro preparations isolated from rats on embryonic day 18 and postnatal days 0-1. The following age-dependent changes occurred: 1) twitch contraction and half relaxation times decreased approximately two- and threefold, respectively; 2) the tetanic force levels increased approximately fivefold; 3) the ratio of peak twitch force to maximum tetanic force decreased 2.3-fold; 4) the range of forces generated by the diaphragm in response to graded nerve stimulation increased approximately twofold; 5) the force-frequency curve was shifted to the right; and 6) the propensity for neuromuscular transmission failure decreased. In conclusion, the diaphragm contractile and phrenic motoneuron repetitive firing properties develop in concert so that the full range of potential diaphragm force recruitment can be utilized and problems associated with diaphragm fatigue are minimized.
fetal breathing; respiration; muscle
This article has been cited by other articles:
|
|
 |
|
  K. P. Carlin, J. Liu, and L. M. Jordan Postnatal Changes in the Inactivation Properties of Voltage-Gated Sodium Channels Contribute to the Mature Firing Pattern of Spinal Motoneurons J Neurophysiol, June 1, 2008; 99(6): 2864 - 2876. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. B. Mantilla and G. C. Sieck Key aspects of phrenic motoneuron and diaphragm muscle development during the perinatal period J Appl Physiol, June 1, 2008; 104(6): 1818 - 1827. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Y. Sebe, J. F. van Brederode, and A. J. Berger Inhibitory Synaptic Transmission Governs Inspiratory Motoneuron Synchronization J Neurophysiol, July 1, 2006; 96(1): 391 - 403. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. J. Greer, G. D. Funk, and K. Ballanyi Preparing for the first breath: prenatal maturation of respiratory neural control J. Physiol., February 1, 2006; 570(3): 437 - 444. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. A. Parkis, J. L. Feldman, D. M. Robinson, and G. D. Funk Oscillations in Endogenous Inputs to Neurons Affect Excitability and Signal Processing J. Neurosci., September 3, 2003; 23(22): 8152 - 8158. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Ren and J. J. Greer Ontogeny of Rhythmic Motor Patterns Generated in the Embryonic Rat Spinal Cord J Neurophysiol, March 1, 2003; 89(3): 1187 - 1195. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Orliaguet, O. Langeron, B. Bouhemad, P. Coriat, Y. LeCarpentier, and B. Riou Effects of postnatal maturation on energetics and cross-bridge properties in rat diaphragm J Appl Physiol, March 1, 2002; 92(3): 1074 - 1082. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Kobayashi, R. P. Lemke, and J. J. Greer Ultrasound measurements of fetal breathing movements in the rat J Appl Physiol, July 1, 2001; 91(1): 316 - 320. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Martin-Caraballo and J. J. Greer Development of Potassium Conductances in Perinatal Rat Phrenic Motoneurons J Neurophysiol, June 1, 2000; 83(6): 3497 - 3508. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
