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Hydrogen peroxide induced responses of cat tracheal smooth muscle cells
Author(s) -
Bauer V,
Oike M,
Tanaka H,
Inoue R,
Ito Y
Publication year - 1997
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0701202
Subject(s) - carbachol , depolarization , membrane potential , chemistry , biophysics , contraction (grammar) , muscle contraction , resting potential , calcium , skeletal muscle , excitatory postsynaptic potential , medicine , endocrinology , stimulation , intracellular , hyperpolarization (physics) , biology , biochemistry , stereochemistry , receptor , nuclear magnetic resonance spectroscopy
The effects of hydrogen peroxide H 2 O 2 (10 −6 and 10 −3 M ) on membrane potential, membrane currents, intracellular calcium concentration, resting muscle tone and contractions elicited by electrical field stimulation (EFS) and carbachol were examined in cat tracheal strips and isolated smooth muscle cells. H 2 O 2 (10 −4 and 10 −5 M ) enhanced the amplitude of contractions and excitatory junction potentials (e.j.p.) evoked by EFS without changing muscle tone and resting membrane potential of the tracheal smooth muscle, and enhanced the contraction induced by carbachol (10 −8 M ). At an increased concentration (10 −3 M ), H 2 O 2 elevated resting muscle tone and marginally hyperpolarized the membrane in the majority of the cells. In 51 out of 56 cells examined, H 2 O 2 (10 −6 –10 −3 M ) elicited an outward current at a holding potential of −40 mV and enhanced the frequency of the spontaneous transient outward current (STOC). In 20 cells the outward current was preceded by a small inward current. In the other cells, H 2 O 2 elicited only an inward current or did not affect the background current. In Ca 2+ free solution the action of H 2 O 2 on the resting muscle tone, STOCs, background current and on the current induced by ramp depolarization was significantly reduced. H 2 O 2 (10 −4 M ) increased the intracellular ionized calcium concentration both in the absence and presence of external Ca 2+ . However, the effect developed faster and was of a higher amplitude in the presence of external Ca 2+ . These results suggest that H 2 O 2 increases intracellular Ca 2+ , with a subsequent augmentation of stimulation‐evoked contractions, and enhances Ca 2+ and voltage‐sensitive potassium conductance.