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Published on: February 9, 2016
Chronic exercise improves endothelial calcium signaling and vasodilatation in hypercholesterolemic rabbit femoral
Chauying J Jen1, Hung-Pin Chan, Hsiun-ing Chen
1Department of Physiology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Objective:
This study was to investigate the effects of chronic exercise on vasodilatation and endothelial intracellular calcium (EC [Ca2+]i) signaling in atherosclerotic animals.
Methods And Results:
For 8 weeks, male New Zealand White rabbits were fed rabbit chow with or without the addition of 2% cholesterol. They were further divided into control and exercise groups. Animals in the exercise groups ran on a leveled treadmill at 0.88 km/h for 10 to 60 minutes gradually for 5 days per week for a total of 8 weeks. At the end of experiments, femoral arteries were dissected, loaded with fura 2-AM, and mounted in a tissue flow chamber. PE-precontracted vessel specimens were exposed to acetylcholine (ACh). The EC [Ca2+]i elevation and vasorelaxation were determined simultaneously under an epifluorescence microscope equipped with a ratio-imaging capability. Our results showed the following: (1) high cholesterol diet feeding caused lipid deposition on vascular surface, reduced the ACh-evoked EC [Ca2+]i elevation, and impaired endothelium-dependent and endothelium-independent vascular responses, but chronic exercise had the opposite effects; (2) ACh-induced vasorelaxation was associated with EC [Ca2+]i elevation in all groups; and (3) vasorelaxation at high levels of EC [Ca2+]i elevation decreased in hypercholesterolemia.
Conclusions:
Our data suggest that hypercholesterolemia induces vascular structural changes and impairs EC [Ca2+]i signaling and vasodilatation, whereas chronic exercise partially reverses these adverse effects.
