Fasting/Refeeding Cycles Prevent Myocardial Dysfunction and Morphology Damage in the Spontaneously Hypertensive Rats

Figures

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  Figure 1. Changes in body weight after 90 days of treatment. Control (C; closed squares, n = 7), animals with food restriction of 50% (R50; closed triangles, n = 7) and animals with alternation between food restriction of 50% and refeeding (RF; open circles, n = 7). Values are means ± SD; * significant at p < 0.05, R50vs. C; † p < 0.05, RF vs. R50; #p < 0.05, C vs. RF. Repeated measures two-way ANOVA; post hoc Bonferroni's test. Source: Research team.

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  Figure 2. Effects of increased extracellular calcium on myocardial isotonic and isometric parameters in papillary muscles from control (C = black bars), animals with food restriction of 50% (R50 = gray bars) and animals with alternation between food restriction of 50% and refeeding (RF = white bars). Extracellular calcium experiment: 7 animals each group. Isometric parameters: A: DT (peak developed tension normalized per cross-sectional area); B: +dT/dt (peak isometric tension development rate normalized per cross-sectional area); C: -dT/dt, g/mm2/s (maximum tension decline rate normalized per cross-sectional area). Isotonic parameters: D: PS (percentage of shortening); E: -dL/dT (maximum shortening velocity); F: +dL/dT (maximum relaxation velocity). Lmax: muscle length at peak DT. Values are means ± SD; * significant at p < 0.05 vs. C; † p < 0.05 vs. R50. Repeated measures two-way ANOVA and post hoc Tukey's test. Source: Research team.

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  Figure 3. Effects of isoproterenol stimulation on myocardial function in papillary muscles from control (C = black bars), animals with food restriction of 50% (R50 = gray bars) and animals with alternation between food restriction of 50% and refeeding (RF = white bars). Isoproterenol stimulation experiment: 7 animals each group. Isometric parameters: A: DT (peak developed tension normalized per cross-sectional area); B: +dT/dt (peak isometric tension development rate normalized per cross-sectional area); C: -dT/dt, g/mm2/s (maximum tension decline rate normalized per cross-sectional area). Isotonic parameters: D: PS (percentage of shortening); E: -dL/dt (maximum shortening velocity at Lmax); F: +dL/dt (maximum relaxation velocity at Lmax). Lmax: muscle length at peak DT. Values are means ± SD; * significant at p < 0.05 vs. C; † p < 0.05 vs. R50.Repeated measures two-way ANOVA and post hoc Tukey's test. Source: Research team.

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  Figure 4. Ultrastructural study of LV papillary muscle (n = 3 per group). Photographs A and B correspond to the control group, photographs C, D and E to the food-restriction (R50) group and photographs F and G to the refeeding group (RF) group. The control group showed preserved ultrastructure with normal myofibrils (M), sarcoplasmic reticulum (arrowhead), mitochondria (mi), nuclear membrane (N) and plasma membrane (arrow). Food restriction rats showed cellular changes, including polymorphic mitochondria (*), myofibril disorganization (**), and infolding of the plasma membrane (arrow). The papillary muscle during refeeding showed preserved myofibrils (M), mitochondria (mi), and plasma membranes (arrow), polymorphic mitochondria (*) and capillary (C). Source: Research team.