Premium
In vivo imaging of intracellular Ca 2+ after muscle contractions and direct Ca 2+ injection in rat skeletal muscle in diabetes
Author(s) -
Eshima Hiroaki,
Tanaka Yoshinori,
Sonobe Takashi,
Inagaki Tadakatsu,
Poole David C,
Kano Yutaka
Publication year - 2013
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.27.1_supplement.1198.1
Subject(s) - endocrinology , medicine , in vivo , contraction (grammar) , skeletal muscle , myocyte , chemistry , streptozotocin , muscle contraction , diabetes mellitus , homeostasis , stimulation , intracellular , calcium , biology , biochemistry , microbiology and biotechnology
The effects of muscle contractions on intracellular Ca 2+ ([Ca 2+ ]i) accumulation kinetics in Type I diabetes are unclear. To test the hypothesis that, following repeated bouts of muscle contractions, the rise in [Ca 2+ ]i evident in healthy rats would be increased in diabetes rats and that these changes would be associated with a decreased cytoplasmic Ca 2+ buffering capacity. Adult male Wistar rats were divided randomly into diabetic (DIA: Streptozotocin i.p.) and healthy (CONT) groups. Four weeks later animals were anesthetized and spinotrapezius muscle contractions (10 sets of 50 contractions) were elicited by electrical stimulation (100 Hz). Ca 2+ imaging was achieved using fura2‐AM in the spinotrapezius muscle in vivo (i.e., circulation intact). The ratio (340/380 nm) was determined from fluorescence images following each contractions set, for estimation of [Ca 2+ ]i. Also, muscle Ca 2+ buffering was studied in individual myocytes microinjected with 2 mM Ca 2+ solution. During muscle contractions, [Ca 2+ ]i in DIA increased earlier and more rapidly than in CONT (P < 0.05 vs. pre‐contraction). Peak [Ca 2+ ]i in response to the Ca 2+ injection was significantly higher in CONT (25.8%) than DIA (10.0%). Diabetes markedly impairs Ca 2+ homeostasis following muscle contractions. Markedly different responses to Ca 2+ injection suggest fundamentally deranged Ca 2+ handling in spinotrapezius muscles of diabetic rats.