Breathing is an innate motor behavior commencing at birth and continuing until the cessation of life. The concerted actions of sensory and motor systems that monitor and adjust the magnitude of ventilation on a breath to breath basis ensure that breathing is commensurate with the oxygen supply and carbon dioxide (CO2) washout. However, the mechanisms involved in coordinating the activity of respiratory rhythm generating neurons with the metabolic demands of the body are not fully understood. Hence the aim of this investigation is to characterize the involvement of inspiratory rhythm-generating neurons in neurochemical control of breathing, specifically inspiratory pacemaker neurons that may be mediating ventilatory responses to CO2/H+ stimulation. The study will focus on rhythmogenic neurons within the pre Botzinger complex as a candidate cell population for CO2/H+ central chemosensory integration. We will specifically describe how respiratory cells respond to pH perturbations occurring in the intra- or extracellular compartments and identify possible membrane mechanisms that contribute to intrinsic chemosensitivity. We will execute electrophysiological and neuroanatomical experiments using in vitro preparations obtained for neonatal rodents. Techniques will include extracellular nerve and single-cell recordings and whole cell perforated patch-clamp. In addition, we will use immunofluorescence, Western blotting, cell culture and in situ hybridization methodologies to define expression of CO2/H+/pH-sensitive substrates within inspiratory rhythm generating neurons. Data obtained from this investigation will provide answers to the fundamental questions related to chemosensory regulation with respect to the contributions of respiratory rhythm generating cells and how dysfunction of this critical population may lead to pathological conditions. These results will have further impact on the understanding of mechanisms occurring in centrally mediated cardiorespiratory dysfunctions such as sudden infant death syndrome (SIDS) and other apneic breathing disorders. ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Scientist Development Award - Research & Training (K01)
Project #
5K01NS047422-05
Application #
7486849
Study Section
NST-2 Subcommittee (NST)
Program Officer
Mitler, Merrill
Project Start
2004-09-01
Project End
2010-08-31
Budget Start
2008-09-01
Budget End
2010-08-31
Support Year
5
Fiscal Year
2008
Total Cost
$137,621
Indirect Cost
Name
Howard University
Department
Physiology
Type
Schools of Medicine
DUNS #
056282296
City
Washington
State
DC
Country
United States
Zip Code
20059
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Johnson, Sheree M; Haxhiu, Musa A; Richerson, George B (2008) GFP-expressing locus ceruleus neurons from Prp57 transgenic mice exhibit CO2/H+ responses in primary cell culture. J Appl Physiol 105:1301-11
Johnson, Sheree M (2008) Pre-Botzinger complex neurokinin-1 receptor expressing neurons in primary cell culture. Adv Exp Med Biol 605:94-8
Wu, Mingfei; Haxhiu, Musa A; Johnson, Sheree M (2005) Hypercapnic and hypoxic responses require intact neural transmission from the pre-Botzinger complex. Respir Physiol Neurobiol 146:33-46