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Selective modulation of membrane currents by hypoxia in intact airway chemoreceptors from neonatal rabbit
Author(s) -
Fu Xiao Wen,
Nurse Colin A.,
Wang Yu Tian,
Cutz Ernest
Publication year - 1999
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1999.139af.x
Subject(s) - hypoxia (environmental) , electrophysiology , patch clamp , biophysics , chemistry , membrane potential , voltage clamp , endocrinology , medicine , anatomy , biology , oxygen , organic chemistry
1 We previously described voltage‐dependent ionic currents and hypoxia chemosensitivity in cultured pulmonary neuroepithelial body (NEB) cells isolated from fetal rabbit. Here we use fresh neonatal rabbit lung slices (200–400 μ m thick) to characterize the electrophysiological properties of ‘intact’ NEBs with patch‐clamp, whole‐cell recording. 2 Under voltage clamp, outward currents were partially inhibited by TEA (20 m m ), 4‐amino pyridine (4‐AP; 2 m m ) and cadmium (Cd 2+ ; 100 μ m ), suggesting the presence of both Ca 2+ ‐dependent ( I K(Ca) ) and Ca 2+ ‐independent ( I K(V) ) components. 3 Inward currents, carried by voltage‐dependent Ca 2+ channels and also, in occasional cells (∼11%), by TTX‐sensitive Na + channels, were also detected in intact NEB cells. 4 Hypoxia ( P O 2= 15–20 mmHg ) reduced the outward K + current by ∼34% during voltage steps from −60 to +30 mV, while inward Ca 2+ or Na + currents were not affected by hypoxia. Hypoxia suppressed roughly equally both I K(Ca) and I K(V) components of outward current, and no further inhibition of K + currents was seen with either TEA and 4‐AP + hypoxia. 5 Diphenylene iodonium (DPI; 1 μ m ) suppressed outward K + current by ∼42%, and DPI + hypoxia had no additional effect on the K + current. 6 Direct application of H 2 O 2 augmented outward K + current; for a voltage step from −60 mV to +30 mV, 0.25 m m H 2 O 2 increased K + current by ∼37%. 7 These results indicate that intact neonatal NEB cells express hypoxic chemosensitivity and introduce the rabbit lung slice preparation as an new model for investigating the role of airway O 2 chemoreceptors.