In vivo electrophysiological responses of pedunculopontine neurons to static muscle contraction.
The pedunculopontine nucleus (PPN) has previously been implicated in central command regulation of the cardiorespiratory adjustments that accompany exercise. The current study was executed to begin to address the potential role of the PPN in the regulation of cardiorespiratory adjustments evoked by muscle contraction. Extracellular single-unit recording was employed to document the responses of PPN neurons during static muscle contraction. Sixty-four percent (20/31) of neurons sampled from the PPN responded to static muscle contraction with increases in firing rate. Furthermore, muscle contraction-responsive neurons in the PPN were unresponsive to brief periods of hypotension but were markedly activated during chemical disinhibition of the caudal hypothalamus. A separate sample of PPN neurons was found to be moderately activated during systemic hypoxia. Chemical disinhibition of the PPN was found to markedly increase respiratory drive. These findings suggest that the PPN may be involved in modulating respiratory adjustments that accompany muscle contraction and that PPN neurons may have the capacity to synthesize muscle reflex and central command influences.
Plowey
Edward D
ED
Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Kramer
Jeffery M
JM
Beatty
Joseph A
JA
Waldrop
Tony G
TG
D000758:Anesthesia; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D004558:Electric Stimulation; D004594:Electrophysiology; D018756:GABA Antagonists / Q000494:pharmacology; D006439:Hemodynamics / Q000502:physiology; D006614:Hindlimb / Q000502:physiology; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D008636:Mesencephalon / Q000166:cytology* / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D009474:Neurons / Q000502:physiology*; D009599:Nitroprusside / Q000494:pharmacology; D011149:Pons / Q000166:cytology* / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015656:Respiratory Mechanics / Q000502:physiology; D013238:Stereotaxic Techniques; D013268:Stimulation, Chemical
D018756:GABA Antagonists; D009599:Nitroprusside; D001640:Bicuculline