Fig. 4. Inotropic effects of ryanodine in isotonic (A ) and isometric (B ) conditions in diaphragm muscle during postnatal maturation. d3 = 3-day-old rats; d10 = 10-day-old rats; d17 = 17-day-old rats; V^max= maximum unloaded shortening velocity; AF = isometric active force normalized per cross-sectional area. Data are mean ± SD. Significant differences between groups refer to P < 0.05.