Exercise training enhances elastin, fibrillin and nitric oxide in the aorta wall of spontaneously hypertensive rats

This work aimed to analyze the effect of low-intensity exercise training on ultrastructural and molecular aortic remodeling. Male Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were allocated into four groups: sedentary WKY (SED-WKY), exercised WKY (EX-WKY, 1 h/day, 5 days/week treadmill exercise training), sedentary SHR (SED-SHR), and exercised SHR (EX-SHR). EX-SHR showed blood pressure reduction of 26% in comparison to SED-SHR after 1 month of exercise (P < 0.05). At the 20th week, BP level was not different between EX-SHRs and WKYs. Circumferential wall tension (CWT) was higher by 77% in SED-SHRs than in SED-WKYs (P < 0.001). Exercise training reduced CWT by 30% in EX- vs. SED-SHR (P < 0.001). In SED-SHRs, endothelial cells showed large and numerous cytoplasmatic vacuoles, fragmented inner elastic lamina and scarce elastin and fibrillin, while exercise training ameliorated it in EX-SHR group. The highest eNOS immunodensity was observed in EX-SHR, which was 50% higher than EX-WKY (P < 0.01) and 120% higher than SED-SHR (P < 0.0001). In conclusion, present findings indicate beneficial effects of exercise training in hypertensive rats since it increased elastin, fibrillin and eNOS content in the aortic wall.

Research Highlights
► Exercise training attenuates tensile forces acting on aortic wall.
► Endothelial ultrastructure is preserved by exercise.
► Exercise training preserves elastin and fibrillin in hypertensive rats.
► Endothelial nitric oxide synthase expression is enhanced by exercise.