title: Multifocal animated imaging of changes in cellular oxygen and calcium concentrations and membrane potential within the intact adult mouse carotid body ex vivo.
abstract: Carotid body (CB) type I cell hypoxia-sensing function is assumed to be based on potassium channel inhibition. Subsequent membrane depolarization initiates an intracellular calcium increase followed by transmitter release for excitation of synapses with linked nerve endings. Several reports, however, contradict this generally accepted concept by showing that type I cell oxygen-sensing properties vary significantly depending on the method of their isolation. We report therefore for the first time noninvasive mapping of the oxygen-sensing properties of type I cells within the intact adult mouse CB ex vivo by using multifocal Nipkow disk-based imaging of oxygen-, calcium- and potential-sensitive cellular dyes. Characteristic type I cell clusters were identified in the compact tissue by immunohistochemistry because of their large cell nuclei combined with positive tyrosine hydroxylase staining. The cellular calcium concentrations in these cell clusters either increased or decreased in response to reduced tissue oxygen concentrations. Under control conditions, cellular potential oscillations were uniform at ∼0.02 Hz. Under hypoxia-induced membrane depolarization, these oscillations ceased. Simultaneous increases and decreases in potential of these cell clusters resulted from spontaneous burstlike activities lasting ∼1.5 s. type I cells, identified during the experiments by cluster formation in combination with large cell nuclei, seem to respond to hypoxia with heterogeneous kinetics.
authors.affiliation: Department of Physiology, University of Duisburg-Essen, Essen, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Wotzlaw
authors.forename: André
authors.initials: A
authors.lastname: Bernardini
authors.forename: Utta
authors.initials: U
authors.lastname: Berchner-Pfannschmidt
authors.forename: Dmitri
authors.initials: D
authors.lastname: Papkovsky
authors.forename: Helmut
authors.initials: H
authors.lastname: Acker
authors.forename: Joachim
authors.initials: J
authors.lastname: Fandrey
mesh_terms: D000814:Aniline Compounds; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002344:Carotid Body / Q000166:cytology / Q000378:metabolism*; D015687:Cell Hypoxia; D005260:Female; D005452:Fluoresceins; D005455:Fluorescent Antibody Technique; D005456:Fluorescent Dyes; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007700:Kinetics; D008564:Membrane Potentials; D051379:Mice; D008810:Mice, Inbred C57BL; D008856:Microscopy, Fluorescence; D009991:Oscillometry; D010100:Oxygen / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism; D056969:Voltage-Sensitive Dye Imaging
chemical_list: D000814:Aniline Compounds; D005452:Fluoresceins; D005456:Fluorescent Dyes; C503942:Oregon green 488 BAPTA-1; D014446:Tyrosine 3-Monooxygenase; D010100:Oxygen; D002118:Calcium