Congenital bilateral vocal cord paralysis and the role of glycine.
OBJECTIVE
We sought to modify normal laryngeal constrictor (LC) motoneuron activity to induce a pattern of aberrant LC muscle function that may serve as a model of congenital bilateral vocal cord paralysis.


METHODS
Single unit extracellular recordings of functionally identified LC motoneurons were made in anesthetized Sprague-Dawley rats, and the response to both intravenous and iontophoretic application of the glycine antagonist strychnine was studied.


RESULTS
The postinspiratory firing pattern of LC motoneurons became inspiratory after intravenous injection of strychnine (4 of 5 rats), but no change was recorded in response to strychnine iontophoresis (7 of 8 rats).


CONCLUSIONS
Blockade of glycinergic inhibitory neurotransmission by strychnine, acting above the level of the LC motoneuron, causes LC motoneurons to fire during inspiration rather than after inspiration. This observation suggests that impaired glycine neurotransmission may be an underlying mechanism that explains the clinical manifestations of congenital bilateral vocal cord paralysis.
Berkowitz
Robert G
RG
Hypertension and Stroke Research Laboratories, Department of Physiology, University of Sydney, Sydney, Australia.
Sun
Qi-Jian
QJ
Pilowsky
Paul M
PM
D000818:Animals; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D018684:Glycine Agents / Q000494:pharmacology*; D007275:Injections, Intravenous; D007478:Iontophoresis; D007821:Laryngeal Muscles / Q000294:innervation; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D010791:Phrenic Nerve / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013331:Strychnine / Q000494:pharmacology*; D014826:Vocal Cord Paralysis / Q000151:congenital* / Q000503:physiopathology
D018684:Glycine Agents; D013331:Strychnine