Intrinsic Regulation of Skeletal Muscle Blood Flow

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Abstract
Isolated, innervated and acutely or chronically denervated resting skeletal muscle of the dog exhibited high intrinsic vascular tone. Sustained alteration of perfusion pressure or venous pressure evoked autoregulatory responses; vascular resistance increased at elevated driving pressures and decreased at reduced driving pressures. Comparable changes of resistance were observed after sustained alteration of blood flow during pump perfusion. Autoregulation was consistently observed during muscle contractions with constant pressure or constant flow perfusion. In resting and contracting skeletal muscle a low venous blood oxygen saturation (VO2) was characteristic of preparations exhibiting a high degree of autoregulation. In innervated resting muscle autoregulation was concealed by reflex or local stimuli and its disappearance was associated with a decreased vascular resistance and an increased VO2. In resting chronically denervated muscle or in contracting muscle, whether innervated or denervated, such stimuli failed to affect the autoregulatory response. A schema has been proposed to define the "states" of skeletal muscle blood flow and some of the factors responsible for the presence or absence of autoregulation.