Hypoxia-induced short-term potentiation of respiratory-modulated facial motor output in the rat.
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.
Lee
Kun-Ze
KZ
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. kzlee@ufl.edu
Fuller
David D
DD
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001784:Blood Gas Analysis / Q000379:methods; D001794:Blood Pressure / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology*; D009046:Motor Neurons / Q000502:physiology*; D010791:Phrenic Nerve / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012119:Respiration; D013997:Time Factors; D014628:Vagotomy / Q000379:methods