Acute Exercise Does Not Alter α‐Adrenergic Responsiveness of Soleus Muscle Arterioles and Feed Arteries

Post‐exercise hypotension may result from diminished vasoconstriction following acute exercise. The purpose of this study was to determine whether one bout of exercise results in diminished α‐adrenergic vasoconstriction in feed arteries and arterioles supplying oxidative muscle. Male Sprague‐Dawley rats were divided into exercise (EX) and control groups (SED). The EX group ran on a treadmill at 30 m/min (15 o incline) until exhaustion while the SED group performed no exercise. Immediately following exercise, first‐order (1A) arterioles and feed arteries (FA) were isolated from the highly oxidative soleus muscle, cannulated, and placed on the stage of an inverted video microscope, which was connected to a monitor and video calipers. The vessels were pressurized and luminal diameter changes were determined in response to cumulative addition of the α 1 ‐adrenergic receptor agonist, phenylephrine (PE, 10 −9 – 10 −4 M), the α 1 ‐ and α 2 ‐adrenergic receptor agonist norepinephrine (NE, 10 −9 – 10 −4 M), and the non‐receptor‐mediated vasoconstrictor, potassium chloride (KCl, 20 – 100 mM). Responsiveness to PE, NE, and KCl was not significantly different following acute exercise in either 1A arterioles or feed arteries from soleus muscle. Thus, it appears that one bout of exercise does not alter α‐adrenergic responsiveness in the vasculature supplying oxidative muscle.