Figure 7. Expression of R146N myosin engenders a restricted cardiac physiology with diastolic dysfunction.

M-mode kymograms generated from high-speed videos of beating 3-week-old PwMhc2/+ and R146N-15/+ hearts. (A) Vertical red lines delineate diastolic diameters. Mutant hearts display cardiac restriction. (B) Horizontal lines demarcate systolic intervals (SI, top) and heart periods (HP, bottom). Mutant hearts display prolonged systolic phases. (C) R146N-15/+ Drosophila exhibit highly significant alterations in several cardiac functional parameters relative to PwMhc2/+ control flies. Both lines were examined at 1- and 3-weeks of age to track potential physiological defects and cardiac remodeling over time. Decreased cardiac dimensions, fractional shortening, and extended periods of systole are observed in 1- and 3-week-old mutants relative to controls. Data are presented as mean ±S.E.M. (N = 40–44 for each genotype and age group) and were evaluated using two-way ANOVAs with Bonferroni multiple comparisons tests. Significance was assessed at p<0.05. Full genotypes are shown in parentheses: PwMhc2/+ (P{PwMhc2}; Mhc¹/+); R146N/+ (Mhc¹/+; P{R146N}).