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Fast and slow Ca2+ transients in intact fast‐twitch skeletal muscle: tissue photometry and 2D confocal detection.
Author(s) -
Payne Anthony M.,
Oca Jose,
Oliver Scott R.,
Clanton Thomas L.
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.600.25
Subject(s) - confocal , biophysics , confocal microscopy , skeletal muscle , chemistry , intracellular , anatomy , microbiology and biotechnology , biology , biochemistry , geometry , mathematics
We previously reported estimates of changes in intracellular [Ca 2+ ] during contractions of mouse diaphragm (dia) bundles. In this study, we sought a fast‐twitch muscle with flat morphology for similar detection. Whole mouse epitrochlearis (epi), primarily MHC IIb, were mounted horizontally, and loaded with 5 μM Rhod‐2 AM or Fluo‐4 AM. A multi‐fiberoptic epifluorescence probe at 90° to the muscle or a 2D array scanning confocal microscope (∼33 Hz) were used for detection. We observed, 1) the signal to noise was greatly enhanced in epi, 2) like dia, epi demonstrated slow Ca +2 transients following tetany, 3) Mn +2 , a quenching agent caused marked reduction in only the fast Ca +2 transients, 4) Ru360, a mito Ca +2 ‐uptake inhibitor, had no effect on the slow Ca +2 transients, 5) Slow Ca +2 transients were reduced in Fluo‐4 compared to Rhod‐2 loaded muscles. 6) Confocal microscopy demonstrated that the slow Ca +2 transients were consistent with mitochondrial Ca +2 . These results demonstrate the feasibility of measuring changes in [Ca +2 ] in intact mammalian fast skeletal muscle and that significant signals arise from mitochondrial sources that, unlike cardiac muscle, are insensitive to Ru360. Supported by NIH 53333