Hypoxia-induced short-term potentiation of respiratory-modulated facial motor output in the rat.

Respir Physiol Neurobiol

University of Florida, College of Public Health and Health Professions, McKnight Brain Institute, Department of Physical Therapy, PO Box 100154, 100 Newell Dr, Gainesville, FL 32610, United States.

Published: August 2010

Respiratory-modulated facial (VII) nerve discharge includes pre-inspiratory (Pre-I) and inspiratory (I) components. Tonic VII bursting is also present across the respiratory cycle. We tested the hypothesis that hypoxia-induced plasticity of VII motor activity is differentially expressed in Pre-I, I and tonic bursting. Phrenic and VII neurograms were recorded in urethane-anesthetized, vagotomized and ventilated adult rats. A 3 min isocapnic hypoxic challenge (PaO(2)=33+/-2 mmHg) was used to evoke respiratory short-term potentiation (STP). Pre-I, I and tonic VII activity increased immediately at the initial stage of hypoxia (i.e. acute response) and then progressively increased as hypoxia was maintained. Following hypoxia, I VII activity remained elevated (i.e. post-hypoxia STP) but both Pre-I and tonic activity immediately returned to baseline values. We conclude that STP following hypoxia is preferentially expressed in I compared to Pre-I and tonic VII activity.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2925412PMC
http://dx.doi.org/10.1016/j.resp.2010.06.015DOI Listing

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