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Rotenone, Mitochondrial Complex I Inhibitor, Augments and Hydrogen Peroxide Inhibits L‐type Calcium Current in Arterial Smooth Muscle Cells
Author(s) -
Ochi Rikuo,
Shah Vidhi,
Patel Dhara,
Wolin Michael,
Gupte Sachin
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.844.10
Subject(s) - rotenone , hydrogen peroxide , calcium , chemistry , myocyte , mitochondrion , pharmacology , microbiology and biotechnology , medicine , biochemistry , biology
L‐type Ca current (ICaL) is a primary Ca current in arterial smooth muscle cells (ASMCs). NADPH oxidase (NOX) generates superoxide (O 2 ‐ ) utilizing NADPH supplied by glucose‐6‐phosphate dehydrogenase (G6PD). O 2 ‐ is generated also from mitochondrial respiratory chain (MRC). O 2 ‐ is dismutated to H 2 O 2 . We studied modulation of ICa,L by O 2 ‐ and H 2 O 2 . Whole‐cell ICa,L was recorded from A7r5 cells derived from embryonic rat aorta and isolated bovine coronary ASMCs. Externally applied H 2 O 2 inhibited ICa,L in a dose‐ and voltage‐dependent manner (50% at 1 mM at holding potential of ‐30 mV) with acceleration of time course of inactivation. The inhibition was rapidly reversible by dithiothreitol. 6‐amino‐nicotinamide, a blocker of G6PD, and apocynin, a blocker of NOX, significantly inhibited ICa,L. Rotenone (Rot), a phytogenic pesticide, inhibits complex I of MRC and increases O 2 ‐ release in bovine coronary ASMCs. Rot dose‐dependently (3 nM‐0.01mM) increased ICa,L (23% at 0.01 mM). The ICa,L increase continued several minutes followed by gradual decrease associated with acceleration of the current decay. When Rot was added during the H 2 O 2 ‐induced inhibition, it augmented ICa,L counteracting the inhibition. When H 2 O 2 was added during the Rot‐induced augmentation, it produced relatively small decrease of the amplitude and facilitated the acceleration of the current decay. The transient nature of the Rot‐induced augmentation is explicable by decrease of O 2 ‐ and increase of H 2 O 2 due to the conversion of O 2 ‐ to H 2 O 2 . Rot increases ICa,L by stimulating O 2 ‐ release from complex I and the increase is followed by the H 2 O 2 ‐induced inhibition.