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This Article Full Text Full Text (PDF) All Versions of this Article: 294/4/R1329    most recent 00815.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Sonobe, T. Articles by Kano, Y. Search for Related Content PubMed PubMed Citation Articles by Sonobe, T. Articles by Kano, Y.

ENVIRONMENTAL, EXERCISE AND RESPIRATORY PHYSIOLOGY

Intracellular calcium accumulation following eccentric contractions in rat skeletal muscle in vivo: role of stretch-activated channels

¹Departments of Applied Physics and Chemistry, University of Electro-Communications, Chofu, Tokyo, Japan; ²Departments of Anatomy, Physiology and Kinesiology, Kansas State University, Manhattan, Kansas; and ³School of Sports and Health Sciences, University of Exeter, Exeter, Devon, United Kingdom

Submitted 9 November 2007 ; accepted in final form 9 January 2008

Although the accumulation of intracellular calcium ions ([Ca²⁺]_i) is associated with muscle damage, little is known regarding the temporal profile of muscle [Ca²⁺]_i under in vivo conditions, and, specifically, the effects of different contraction types [e.g., isometric (ISO); eccentric (ECC)] on [Ca²⁺]_i remain to be determined. The following hypotheses were tested. 1) For 90 min at rest, an in vivo vs. in vitro preparation would better maintain initial [Ca²⁺]_i. 2) Compared with ISO, ECC contractions (50 contractions, 10 sets, 5-min interval) would lead to a greater increase of [Ca²⁺]_i. 3) Elevated [Ca²⁺]_i during ECC would be reduced or prevented by the stretch-activated ion channel blockers streptomycin and gadolinium (Gd³⁺). Spinotrapezius muscles of Wistar rats were exteriorized (in vivo) or excised (in vitro). [Ca²⁺]_i was evaluated by loading the muscle with fura 2-AM using fluorescence imaging. [Ca²⁺]_i rose progressively beyond 40 min at rest under in vitro but not in vivo conditions during the 90-min protocol. In vivo [Ca²⁺]_i increased more rapidly during ECC (first set) than ISO (fifth set) (P < 0.05 vs. precontraction values). The peak level of [Ca²⁺]_i was increased by 21.5% (ISO) and 42.8% (ECC) after 10 sets (both P < 0.01). Streptomycin and Gd³⁺ abolished the majority of [Ca²⁺]_i increase during ECC (69 and 86% reduction, respectively; P < 0.01 from peak [Ca²⁺]_i of ECC). In conclusion, in vivo quantitative analyses demonstrated that ECC contractions elevate [Ca²⁺]_i significantly more than ISO contractions and that stretch-activated channels may play a permissive role in this response.

spinotrapezius; muscle damage; streptomycin; gadolinium

This article has been cited by other articles:

				S. J. Choi and J. J. Widrick Combined effects of fatigue and eccentric damage on muscle power J Appl Physiol, October 1, 2009; 107(4): 1156 - 1164. [Abstract] [Full Text] [PDF]