title: Chronic hypoxia suppresses the CO2 response of solitary complex (SC) neurons from rats.
abstract: We studied the effect of chronic hypobaric hypoxia (CHx; 10-11% O(2)) on the response to hypercapnia (15% CO(2)) of individual solitary complex (SC) neurons from adult rats. We simultaneously measured the intracellular pH and firing rate responses to hypercapnia of SC neurons in superfused medullary slices from control and CHx-adapted adult rats using the blind whole cell patch clamp technique and fluorescence imaging microscopy. We found that CHx caused the percentage of SC neurons inhibited by hypercapnia to significantly increase from about 10% up to about 30%, but did not significantly alter the percentage of SC neurons activated by hypercapnia (50% in control vs. 35% in CHx). Further, the magnitudes of the responses of SC neurons from control rats (chemosensitivity index for activated neurons of 166+/-11% and for inhibited neurons of 45+/-15%) were the same in SC neurons from CHx-adapted rats. This plasticity induced in chemosensitive SC neurons by CHx appears to involve intrinsic changes in neuronal properties since they were the same in synaptic blockade medium.
authors.affiliation: Department of Neuroscience, Cell Biology & Physiology, Wright State University Boonshoft School of Medicine, 3640 Colonel Glenn Highway, Dayton, OH 45435, USA.
authors.forename: Nicole L
authors.initials: NL
authors.lastname: Nichols
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Wilkinson
authors.forename: Frank L
authors.initials: FL
authors.lastname: Powell
authors.forename: Jay B
authors.initials: JB
authors.lastname: Dean
authors.forename: Robert W
authors.initials: RW
authors.lastname: Putnam
mesh_terms: D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000222:Adaptation, Physiological / Q000187:drug effects; D000818:Animals; D002245:Carbon Dioxide / Q000494:pharmacology*; D002628:Chemoreceptor Cells / Q000187:drug effects* / Q000502:physiology; D004195:Disease Models, Animal; D006400:Hematocrit / Q000379:methods; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D006935:Hypercapnia / Q000503:physiopathology*; D000860:Hypoxia / Q000473:pathology*; D066298:In Vitro Techniques; D008297:Male; D009433:Neural Inhibition / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000473:pathology*; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide