title: Strain differences in pH-sensitive K+ channel-expressing cells in chemosensory and nonchemosensory brain stem nuclei.
abstract: The ventilatory CO2 chemoreflex is inherently low in inbred Brown Norway (BN) rats compared with other strains, including inbred Dahl salt-sensitive (SS) rats. Since the brain stem expression of various pH-sensitive ion channels may be determinants of the CO2 chemoreflex, we tested the hypothesis that there would be fewer pH-sensitive K(+) channel-expressing cells in BN relative to SS rats within brain stem sites associated with respiratory chemoreception, such as the nucleus tractus solitarius (NTS), but not within the pre-Bötzinger complex region, nucleus ambiguus or the hypoglossal motor nucleus. Medullary sections (25 μm) from adult male and female BN and SS rats were stained with primary antibodies targeting TASK-1, Kv1.4, or Kir2.3 K(+) channels, and the total (Nissl-stained) and K(+) channel immunoreactive (-ir) cells counted. For both male and female rats, the numbers of K(+) channel-ir cells within the NTS were reduced in the BN compared with SS rats (P < 0.05), despite equal numbers of total NTS cells. In contrast, we found few differences in the numbers of K(+) channel-ir cells among the strains within the nucleus ambiguus, hypoglossal motor nucleus, or pre-Bötzinger complex regions in both male and female rats. However, there were no predicted functional mutations in each of the K(+) channels studied comparing genomic sequences among these strains. Thus we conclude that the relatively selective reductions in pH-sensitive K(+) channel-expressing cells in the NTS of male and female BN rats may contribute to their severely blunted ventilatory CO2 chemoreflex.
authors.affiliation: Biology Department, Carthage College, Kenosha, Wisconsin; Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
authors.forename: Paul F
authors.initials: PF
authors.lastname: Martino
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
authors.forename: S
authors.initials: S
authors.lastname: Olesiak
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
authors.forename: D
authors.initials: D
authors.lastname: Batuuka
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
authors.forename: D
authors.initials: D
authors.lastname: Riley
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin;
authors.forename: S
authors.initials: S
authors.lastname: Neumueller
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin; and.
authors.forename: H V
authors.initials: HV
authors.lastname: Forster
authors.affiliation: Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin; Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin mhodges@mcw.edu.
authors.forename: M R
authors.initials: MR
authors.lastname: Hodges
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000378:metabolism* / Q000502:physiology*; D002245:Carbon Dioxide / Q000378:metabolism; D002628:Chemoreceptor Cells / Q000378:metabolism*; D005260:Female; D008297:Male; D015221:Potassium Channels / Q000378:metabolism*; D051381:Rats; D011914:Rats, Inbred BN; D020303:Rats, Inbred Dahl
chemical_list: D015221:Potassium Channels; D002245:Carbon Dioxide
keywords: CO2 chemoreception; K+ channels; control of breathing