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Adrenergic Regulation of Vasomotor Responses in Skeletal Muscle Composed of Different Fiber Types
Author(s) -
Behnke Brad J,
Armstrong Robert B.,
Delp Michael D
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.787.12
Subject(s) - endocrinology , medicine , vasoconstriction , phenylephrine , denervation , soleus muscle , skeletal muscle , blood flow , chemistry , clonidine , oxidative phosphorylation , gastrocnemius muscle , vascular smooth muscle , vascular resistance , anatomy , hemodynamics , blood pressure , biochemistry , smooth muscle
The sympathetic nervous system (SNS) has a profound ability to control blood flow and vascular resistance in skeletal muscle at rest and during exercise. The purpose of this study was to further elucidate the influence of the SNS on vasoconstrictor tone in muscles composed of different fiber types. Blood flow to the red (R Gast ) and white (W Gast ) portions of the gastrocnemius and the soleus muscles were measured pre‐ and post‐denervation, and dose‐response relations to alpha 1 (phenylephrine) or alpha 2 (clonidine) adrenoreceptor agonists were determined in isolated arterioles from these muscles. Denervation increased blood flow 8.7‐fold in the fast low‐oxidative muscle W Gast while only eliciting an ∼2.7‐fold increase in the slow oxidative (soleus) and fast oxidative (R Gast ) muscles. In arterioles, sensitivity to phenylephrine was greater in W Gast and R Gast versus the soleus muscle, whereas vasoconstriction to clonidine was greater in W Gast (~50%) relative to that in R Gast (~31%) and soleus (~17%). These data indicate 1) an intermediate control of vascular resistance by the SNS in fast oxidative muscle versus the other muscle types, and 2) the SNS influence on blood flow could fully account for the magnitude of the hyperemia observed during exercise in fast low‐oxidative muscle.