Time-course of endothelial adaptation following acute and regular exercise.
BACKGROUND
Regular exercise training has emerged as a powerful tool to improve endothelium-dependent vasorelaxation. However, little is known about the magnitude of change and the permanence of exercise-induced adaptations in endothelial function.


METHODS
Rats were randomized to either 6 weeks of regular exercise or one bout of exercise. Rats were then sacrificed 0, 6, 12, 24, 48, 96 or 192 h post-exercise, and vascular responsiveness to acetylcholine was determined.


METHODS
Endothelium-dependent dilation was assessed by exposure to accumulating doses of acetylcholine in ring segments of the abdominal aorta from female Sprague-Dawley rats that either exercised regularly for 6 weeks or performed a single bout of exercise.


RESULTS
A single exercise session improved endothelium-dependent vasodilatation for about 48 h. Six weeks of regular exercise induced a significantly larger improvement that lasted for about 192 h. Sensitivity to acetylcholine was twofold higher in chronically trained animals than in those exposed to a single bout of exercise. The decay after a single bout of exercise was about eightfold faster than that after 6 weeks of training.


CONCLUSIONS
The present data extend our concept of exercise-induced adaptation of endothelium-dependent vasodilatation in two regards: (1) a single bout of exercise improves endothelium-dependent dilation for about 2 days, with peak effect after 12-24 h; (2) regular exercise further improves adaptation and increases the sensitivity to acetylcholine approximately fourfold, which slowly returns to sedentary levels within a week of detraining.
Haram
Per Magnus
PM
Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
Adams
Volker
V
Kemi
Ole Johan
OJ
Brubakk
Alf O
AO
Hambrecht
Rainer
R
Ellingsen
Oyvind
O
Wisløff
Ulrik
U
D000109:Acetylcholine / Q000494:pharmacology; D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001012:Aorta, Abdominal / Q000187:drug effects / Q000502:physiology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005500:Follow-Up Studies; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000379:methods*; D005082:Physical Exertion / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*; D014665:Vasodilator Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014665:Vasodilator Agents; D009569:Nitric Oxide; D000109:Acetylcholine; D019331:NG-Nitroarginine Methyl Ester