FIGURE 9.

Force and Ca²⁺ transients in intact transgenic papillary muscle fibers. Shown are force (a) and [Ca²⁺](b) transients in Tg-R145G (n = 9) versus Tg-WT (n = 9) intact papillary fibers. Also shown are force (c) and [Ca²⁺](d) transients in NTg (n = 5) versus Tg-WT intact papillary fibers. Intact papillary muscle fibers were stimulated at 1.0 HZ. Fluorescence produced by Fura-2 was recorded at the same time (see “Materials and Methods” for details). As shown, force and [Ca²⁺] transients are both prolonged in Tg-R145G fibers compared with Tg-WT fibers. As predicted, force and [Ca²⁺] transients do not have significant difference in Tg-WT fibers compared with NTg fibers. Data are expressed as the mean of n (n = 5-9) experiments ± S.E.