In vivo imaging of intracellular calcium following skeletal muscle contractions in type I diabetes rat

 

Yutaka Kano, Takashi Sonobe, Tadakatsu Inagaki, and Mizuki Sudo

Department of Applied Physics and Chemistry, University of Electro-Communications, Chofu, Tokyo, Japan

 

Maintenance of calcium homeostasis for muscle contractions is associated with muscle fatigue and muscle damage. The effects of different muscle contraction types (isometric contraction: ISO, eccentric contraction: ECC) on intracellular calcium [Ca²⁺]i  accumulation kinetics are unclear in diabetes. To test the hypothesis that, following repeated bouts of ISO or ECC (total of 10 sets of 50 contractions), the rise in [Ca²⁺]i evident would be increased in diabetes rats than in normal rats. The experiments were performed by Ca²⁺ imaging using fura2-AM in rat spinotrapezius muscle in vivo. Adult male Wistar rats were divided randomly into diabetic (DIA: Streptozotocin i.p.) and nondiabetic groups CONT). Change of fluorescence ratio (340/380 nm) used to estimate [Ca²⁺]i. During ISO, [Ca²⁺]i in DIA (3 sets) increased more rapidly than CONT (6 sets) (P<0.05 vs. pre-contraction). Although the ECC protocol induced a significant  [Ca²⁺]i increase after the first set of contraction in both CONT and DIA, there were no significant differences between CONT and DIA. In conclusion, in healthy muscle, ECC induced [Ca²⁺]i accumulation was larger and faster compared with ISO. However, diabetic muscular [Ca²⁺]i accumulation by ISO reached the level of ECC.

 

Key word: Muscle damage , Bio-imaging , Calcium ion