Effects of Aging and Exercise Training on the Mechanisms of Angiotensin Ii-induced Vasoconstriction in Rat Skeletal Muscle Arterioles

Effects of Aging and Exercise Training on the Mechanisms of Angiotensin II-Induced Vasoconstriction in Rat Skeletal Muscle Arterioles. (December 2006) Yoonjung Park, B.A., Seoul National University; M.S., Seoul National University; M.A., The University of Texas at Austin Chair of Advisory Committee: Dr. Robert B. Armstrong Aging is associated with increases in regional and systemic vascular resistance and impaired ability to increase blood flow to active muscles during exercise. Aging enhances vasoconstrictor responsiveness in both humans and animals, and an increase in Angiotensin II-induced vasoconstriction is one possible mechanism for old ageassociated increase in muscle vascular resistance. The purpose of this study was to determine 1) whether aging alters Ang II-induced vasoconstriction, 2) whether exercise training attenuates the age-associated alteration in Ang II-mediated vasoconstriction, and 3) the mechanism(s) through which aging and exercise training alter Ang II-induced vasoconstriction in rat skeletal muscle arterioles. Male Fischer 344 rats were assigned to 4 groups: Young sedentary (YS; 4 months), old sedentary (OS; 24 months), young trained (YT) and old trained (OT). Exercise-trained groups performed treadmill exercises for 60 min/day at 15 m/min, on a 15o incline for 5 days/week for 10-12 weeks. First-order (1A) arterioles were isolated from soleus and gastrocnemius muscles for in