Quantification of collagen and F-actin. Quantification of collagen and F-actin were based on signal thresholding of matched LV endocardial areas from each group (n = 7 per group). To avoid possible effects of orientation and origin of the muscle fibres on the quantification, three transverse optical sections per animal were analyzed. Results have been expressed as percentages of corresponding cross-sectional areas. (A) A representative image illustrating application of the signal thresholding procedure. Mask1 eliminated the unlabelled area; mask2 additionally removed the F-actin labelled area. (B) Histogram of representative images from the three experimental groups showing the thresholds used for quantification. The criteria used for the thresholding process were maintained the same for each of the three experimental groups. The threshold setup for quantifying F-actin labelling was based on both the original image and the image following application of mask1. The threshold setup for quantifying collagen labelling was based on both the original image and the image after application of both mask1 and mask2. Shadowed areas represent signals used for quantification. (C) Results show that diabetic rats had increased type-I collagen content compared to controls (Diabetic: 7.1 ± 0.1% area; Control: 6.2 ± 0.2% area, P = 0.003), and TETA prevented this increase by retaining normal values (TETA-treated diabetic: 6.6 ± 0.1% area, P = 0.008). Diabetic rats also developed lowered F-actin content compared to control rats (Diabetic: 56.9 ± 0.6% area; Control: 61.7 ± 0.4% area, P < 0.0001); whereas, TETA-treatment prevented the lowering of F-actin values (TETA-treated diabetic: 60.4 ± 0.5% area, P < 0.0001). Type-III collagen did not differ significantly between groups. Data are means ± SEM, one-way ANOVA with post-hoc Tukey’s Multiple Comparisons test. * C vs D; † D vs D + T; P < 0.05.