Direct coupling between blood flow and metabolism at the capillary level in striated muscle

Abstract

In hamster cremaster muscle, capillary networks consist of anatomically invariant subunits termed modules [Berg, B. R., and I. H. Sarelius, Am. J. Physiol. 268 (Heart Circ. Physiol. 37): H1215-H1222, 1995]. To explore local coupling between blood flow and metabolism, we used micropipettes to stimulate five to six muscle fibers running underneath specified capillary modules. Capillary erythrocyte flow increased significantly at all stimulation frequencies because of increased erythrocyte content at 2 Hz and increased erythrocyte velocity at 4 and 8 Hz. Erythrocyte flow did not increase when the fibers underlying the module were mechanically tugged but did not actively contract at these frequencies. Increased capillary flow was accommodated by dilation of three upstream arteriolar generations: the module inflow arteriole dilated significantly at all frequencies, and further upstream, dilations were significant at higher frequencies. Other module inflow arterioles in the same capillary network as the stimulated module did not dilate. Dilations in the module inflow arteriole were abolished by 600 mosM sucrose but were unaffected by 10(-6) M tetrodotoxin. These data suggest that local coupling between capillary flow and muscle contraction includes a conducted vasodilation that is responsible for the remote upstream dilations.

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

“…We consider that the remarkable autonomic innervation of the pig BSM could be attributed, primarily, to the vascular contingent of the muscle, as it has already been demonstrated for the vessels of the rat cremaster muscle (CM) (Grant, 1966), of guinea-pig limb muscles (Grasby et al, 1997) and human skeletal muscle (Saito et al, 1997). 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).…”

Coupling between skeletal muscle fiber size and capillarization is maintained during healthy aging

“…Mitochondria may not work maximally during contractile activity, and a heterogeneous capillary perfusion57, 58 affecting tissue oxygenation59 may help match oxygen demand and delivery. Such a functional connectivity between active muscle fibres, their surrounding capillaries and the arterioles is well known 60, 61. Nevertheless, the 100‐fold variation in maximal oxygen demand supported by a capillary deviates from the concept of symmorphosis, which states that structures and demand are matched 62.…”

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).…”