Respiratory rhythm: an emergent network property?
We tested the hypothesis that pacemaker neurons generate breathing rhythm in mammals. We monitored respiratory-related motor nerve rhythm in neonatal rodent slice preparations. Blockade of the persistent sodium current (I(NaP)), which was postulated to underlie voltage-dependent bursting in respiratory pacemaker neurons, with riluzole (< or =200 microM) did not alter the frequency of respiratory-related motor output. Yet, in every pacemaker neuron recorded (50/50), bursting was abolished at much lower concentrations of riluzole (< or =20 microM). Thus, eliminating the pacemaker population (our statistics confirm that this population is reduced at least 94%, p < 0.05) does not affect respiratory rhythm. These results suggest that voltage-dependent bursting in pacemaker neurons is not essential for respiratory rhythmogenesis, which may instead be an emergent network property.
Del Negro
Christopher A
CA
Systems Neurobiology Laboratory, Department of Neurobiology, University of California-Los Angeles, Box 95-1763, 90095, USA. delnegro@ucla.edu
Morgado-Valle
Consuelo
C
Feldman
Jack L
JL
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004525:Efferent Pathways / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D007002:Hypoglossal Nerve / Q000187:drug effects / Q000502:physiology; D008526:Medulla Oblongata / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D051379:Mice; D009415:Nerve Net / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009924:Organ Culture Techniques; D010507:Periodicity; D051381:Rats; D012119:Respiration / Q000187:drug effects*; D012125:Respiratory Center / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D019782:Riluzole / Q000494:pharmacology; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology; D013116:Spinal Cord / Q000187:drug effects / Q000254:growth & development* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D015222:Sodium Channels; D019782:Riluzole