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Role of Mitochondria in SR Calcium Buffering in Human Airway Smooth Muscle
Author(s) -
Yang Binxia,
Thompson Michael,
Prakash Y S,
Pabelick Christina
Publication year - 2009
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.23.1_supplement.622.4
Subject(s) - mitochondrion , ryanodine receptor , uniporter , calcium , chemistry , cyclopiazonic acid , microbiology and biotechnology , biophysics , calcium signaling , ruthenium red , trpc3 , cytosol , endoplasmic reticulum , intracellular , biology , biochemistry , receptor , transient receptor potential channel , organic chemistry , trpc , enzyme
Sarcoplasmic reticulum (SR) Ca 2+ release and reuptake are important mechanisms in airway smooth muscle (ASM) intracellular Ca 2+ [Ca 2+ ] i regulation. In other tissues, there is increasing evidence for a role of mitochondria in [Ca 2+ ] i buffering, especially following SR Ca 2+ release. Mitochondrial buffering may also influence Ca 2+ influx. The purpose of the present study was to examine the role of mitochondria in [Ca 2+ ] i buffering in human ASM. Cells were loaded with fura‐2 and exposed to 10 µM histamine in "0" Ca 2+ HBSS containing 1mM lanthanum and 1µM nifedipine (to block Ca 2+ influx/efflux) and in the additional presence of 1µM RU360 (mitochondrial Ca 2+ uniporter inhibitor) or 1µM CGP37157 (CGP; mitochondrial Na + /Ca 2+ exchange inhibitor). Compared to controls, peak [Ca 2+ ] i levels were increased by 30% in the presence of CGP, while RU360 had not effect. Both CGP and RU360 significantly increased store‐operated Ca 2+ entry. In cells co‐loaded with fura‐2 and rhod‐2 (mitochondrial Ca 2+ indicator), exposure to 5 µM caffeine showed instantaneous SR Ca 2+ release followed by an increase in [Ca 2+ ] mito . Exposure to 1 µM ACh resulted in ACh‐induced [Ca 2+ ] i oscillations that were reflected by mitochondria (but with a time delay). In ASM cells co‐labeled for mitochondria (MitoTracker) and SR (fluorescent ryanodine) migration of mitochondria towards SR was observed upon exposure to ACh or cyclopiazonic acid. This migration was completely inhibited by phalloidin (actin inhibitor). These data demonstrate an important role of mitochondria in [Ca 2+ ] i buffering in ASM. Supported by NIH grant RR024150, and the Flight Attendants Medical Research Institute (FAMRI). Additional funding from the Department of Anesthesiology, Mayo Clinic.