Neural control of muscle blood flow during exercise

Abstract

.-Activation of skeletal muscle fibers by somatic nerves results in vasodilation and functional hyperemia. Sympathetic nerve activity is integral to vasoconstriction and the maintenance of arterial blood pressure. Thus the interaction between somatic and sympathetic neuroeffector pathways underlies blood flow control to skeletal muscle during exercise. Muscle blood flow increases in proportion to the intensity of activity despite concomitant increases in sympathetic neural discharge to the active muscles, indicating a reduced responsiveness to sympathetic activation. However, increased sympathetic nerve activity can restrict blood flow to active muscles to maintain arterial blood pressure. In this brief review, we highlight recent advances in our understanding of the neural control of the circulation in exercising muscle by focusing on two main topics: 1) the role of motor unit recruitment and muscle fiber activation in generating vasodilator signals and 2) the nature of interaction between sympathetic vasoconstriction and functional vasodilation that occurs throughout the resistance network. Understanding how these control systems interact to govern muscle blood flow during exercise leads to a clear set of specific aims for future research.

Effect of gender on training-induced vascular remodeling in SHR

“…Late vasodilatation is mostly mediated by accumulation of local vasoactive compounds, which act directly on the vessel wall and indirectly to block sympathetic activation (functional sympatholysis). Indeed several investigators have confirmed that sympathetic vasomotor innervation is activated during exercise (52,(54)(55)(56). Despite the similar local vasodilatation occurring in both groups, relative flow at high exercise load was significantly higher in trained SHR than in trained WKY ( Figure 5), suggesting the involvement of other factor(s).…”

“…The mechanisms controlling blood flow during exercise are still controversial. Removal of a sympathetic vasoconstrictor (responsible for maintaining resting vascular tone) (54), accumulation of local metabolic vasodilators such as adenosine, nitric oxide, osmolarity, high CO 2 , low O 2 and pH (52,54) and high activity of the muscle pump (55) are proposed mechanisms.…”

Striated Perineal Muscles: Location of Autonomic, Sensory, and Somatic Neurons Projecting to the Male Pig Bulbospongiosus Muscle

“…Autonomic control of vasomotor functions could be involved in muscle metabolism (Grant, 1966;Baez, 1973;Fleming et al, 1987Fleming et al, , 1989Franken et al, 1996;Berg et al, 1997;Kurjiaka, 2004). In fact, during skeletal muscle contraction it is possible to observe a local functional vasodilation, rapidly followed by a sympathetic vasoconstriction (Thomas and Segal, 2004). Initially the rhythmic skeletal muscle contractions augment capillary perfusion (Sweeney and Sarelius, 1989) and promote the extraction of oxygen and nutrients from the blood (functional vasodilation) (Gorczynski et al, 1978;Marshall and Tandon, 1984;Van Teeffelen and Segal, 2003).…”

Sensory and Autonomic Neurons Project Both to the Smooth Retractor Penis and to the Striated Bulbospongiosus Muscles. Neurochemical Features of the Sympathetic Subset

“…The autonomic control of vasomotor functions could be involved in the muscles metabolism (Grant, 1966;Baez, 1973;Fleming et al, 1987Fleming et al, , 1989Franken et al, 1996;Berg et al, 1997;Kurjiaka, 2004). In fact, during the contraction of a muscle it is possible to observe a local functional vasodilatation, quickly followed by a sympathetic vasoconstriction (Thomas and Segal, 2004). Initially, the contraction of muscle augment capillary perfusion (Sweeney and Sarelius, 1989) promote the extraction of oxygen and nutrients from the blood (functional vasodilation) (Gorczynski et al, 1978;Marshal and Tandon, 1984;Van Teeffelen and Segal, 2003).…”