Exercise Training Induces Functional Remodeling Of Cardiovasculature And Thoracic Aorta Smooth Muscle Cells In Rats

Introduction:To investigate the functional remodeling of cardiovasculature and thoracic aorta smooth muscle cells induced by aerobic exercise training and to explore the possible mechanisms.Methods:Male Wistar rats (2M), were randomly divided into two groups, sedentary control group (SD) and aerobic exercise training group (Ex). In vivo study and in vitro study were carried on these two groups. Aerobic exercise training on the treadmill was applied on Ex group for 8 weeks. After 8 weeks, the rats were operated with femoral venous cannulation, and the basal blood pressure, heart rate and the cardiovascular responses after intravenous (i.v.) injection of AngII, NE and specific K+ channel blockers were monitored in vivo. In in vitro study, the thoracic aorta was collected, the endothelium was removed, and the vascular rings were prepared. AngII, NE, TEA,4-AP, NS1619 and pinacidil were applied to the aorta rings to investigate the vessel reaction induced by exercises.Rasults:(1) The mean arterial pressure of rats had a tendency to decrease but there was no significant difference between SD and Ex groups. However, the heart rate was markedly decreased after exercise training. (2) The pressor responses induced by i. v. injection of AngII 1μg/Kg) and NE(18μg/Kg) were attenuated in Ex group compared with the SD group, and the heart rate was significantly decreased. (3) The pressor responses induced by i.v. injection of different K+ channel blocker such as TEA (40mg/Kg), Iberiotoxin (6.5μg/Kg),4-AP (1.3mg/Kg), and glibenclamide (20mg/Kg) was significantly enhanced after exercise training; the heart rate decreased after Iberiotoxin and 4-AP injection, but did not change after glibenclamide and TEA injection. (4) Ang II and NE caused a significantly increase of vascular tone in a concentration dependent manner in both groups, while the increase amplitude was less in Ex group than in the SD group. (5) Both TEA and 4-AP could induce an increase of vessel contractility in two groups, while the amplitude of increase was significantly enhanced after exercise training. (6) In Ex group, the vessel dilation induced by NS1619 and pinacidil was more significant than SD group. Conclusion:(1) Aerobic exercise training can reduce heart rate in rats, ease high blood pressure caused by vasoconstrictor, improve the function of cardiovasculature. (2) Aerobic exercise training can reduce the reaction of vascular smooth muscle caused by the vasoconstrictor. (3) Aerobic exercise training can enhance the contraction of aortic smooth muscle caused by the potassium channel blocker.