Malfunction of respiratory-related neuronal activity in Na+, K+-ATPase alpha2 subunit-deficient mice is attributable to abnormal Cl- homeostasis in brainstem neurons.
Na+, K+-ATPase 2 subunit gene (Atp1a2) knock-out homozygous mice (Atp1a2-/-) died immediately after birth resulting from lack of breathing. The respiratory-related neuron activity in Atp1a2-/- was investigated using a brainstem-spinal cord en bloc preparation. The respiratory motoneuron activity recorded from the fourth cervical ventral root (C4) was defective in Atp1a2-/- fetuses of embryonic day 18.5. The C4 response to electrical stimulation of the ventrolateral medulla (VLM) recovered more slowly in Atp1a2-/- than in wild type during superfusion with Krebs' solution, consistent with the high extracellular GABA in brain of Atp1a2-/-. Lack of inhibitory neural activities in VLM of Atp1a2-/- was observed by optical recordings. High intracellular Cl- concentrations in neurons of the VLM of Atp1a2-/- were detected in gramicidin-perforated patch-clamp recordings. The alpha2 subunit and a neuron-specific K-Cl cotransporter KCC2 were coimmunoprecipitated in a purified synaptic membrane fraction of wild-type fetuses. Based on these results, we propose a model for functional coupling between the Na+, K+-ATPase alpha2 subunit and KCC2, which excludes Cl- from the cytosol in respiratory center neurons.
Ikeda
Keiko
K
Division of Biology, Center for Molecular Medicine, Jichi Medical School, Kawachi, Tochigi 329-0498, Japan.
Onimaru
Hiroshi
H
Yamada
Junko
J
Inoue
Koichi
K
Ueno
Shinya
S
Onaka
Tatsushi
T
Toyoda
Hiroki
H
Arata
Akiko
A
Ishikawa
Tomo-o
TO
Taketo
Makoto M
MM
Fukuda
Atsuo
A
Kawakami
Kiyoshi
K
D000595:Amino Acid Sequence; D000818:Animals; D001049:Apnea / Q000196:embryology / Q000235:genetics / Q000503:physiopathology; D002712:Chlorides / Q000378:metabolism*; D004558:Electric Stimulation; D005154:Facial Nerve / Q000502:physiology; D005333:Fetus / Q000378:metabolism / Q000502:physiology; D006706:Homeostasis / Q000502:physiology; D007527:Isoenzymes / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009433:Neural Inhibition / Q000502:physiology; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000378:metabolism; D012125:Respiratory Center / Q000166:cytology / Q000196:embryology / Q000378:metabolism* / Q000502:physiology; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics / Q000502:physiology*; D013126:Spinal Nerve Roots / Q000502:physiology; D027981:Symporters / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology; D000096922:K Cl- Cotransporters
D002712:Chlorides; D007527:Isoenzymes; D011188:Potassium; D000254:Sodium-Potassium-Exchanging ATPase; D027981:Symporters; D005680:gamma-Aminobutyric Acid; D000096922:K Cl- Cotransporters; C401838:Atp1a2 protein, mouse