Abstract 13630: Regional Ros Production Causes Ca2+ Waves in the Myocardium with Nonuniform Contraction

Introduction: In diseased hearts, Ca2+ is dissociated from the myofilaments during the relaxation phase due to the paradoxical shortening of the impaired muscle by relaxation of the more viable neighboring muscle. This dissociated Ca2+ initiates Ca2+ waves from the border zone (BZ) between the impaired muscle and the viable muscle. It is still unclear, however, why Ca2+ waves can be initiated from the BZ but not from the impaired muscle. We examined whether reactive oxygen species (ROS) production plays a role in their initiation using the myocardium with nonuniform contraction. Methods: Trabeculae were dissected from rat hearts. Force was measured with a strain gauge, and intracellular Ca2+ (Cai) with fura-2 and a CCD camera. To assess ROS production, the fluorescence of 2’,7’-dichlorofluorescein (DCF) was measured with a CCD camera. Nonuniform contraction was produced by a jet of 2,3-butanedione monoxime (20 mM) solution. Ca2+ waves were induced by stimulation at 400 ms intervals for 7.5 s (24oC, Cao 2....