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Vasomotor control mechanisms operant in skeletal muscle in the endothelium and vascular smooth muscle cells in the walls of arteries and arterioles (upper panel). Lower panel illustrates some of the more prominent receptors, ion channels, and signaling pathways that operate to modulate vascular smooth muscle tone in skeletal muscle as these emphasize the complex nature of the neurohumoral and metabolic regulatory systems involved in the control of vascular resistance in skeletal muscle at rest and during exercise. The illustration is not meant to be all-inclusive. Pericytes are not depicted, but are discussed in the text, as these contractile cells may also participate in vasomotor control. Modified from reference [365]. In both panels, the internal elastic lamina (basement membrane) between the endothelium and vascular smooth muscle is omitted for clarity.
Abbreviations: K_Ca, calcium-activated K⁺ channel; K_ATP, ATP-sensitive K⁺ channel; K_v, voltage-gated K⁺ channel; K_IR, inward rectifying K⁺ channel; Trp, transient receptor potential channels; O₂, oxygen; ATP, adenosine triphosphate; NO, nitric oxide; TXA₂, thromboxane A₂ and receptor; 5HT, 5-hydroxytryptamine and receptor; PMNs, polymorphonuclear leukocytes; O₂^-, superoxide anion radical; H₂O₂, hydrogen peroxide; TNF, tumor necrosis factor α; LTC₄, leukotriene C₄; MMP, matrix metalloproteinases; P2, purinergic type 2 receptor; M, muscarinic receptor; MEJ, myoendothelial junction; H₁ and H₂, histamine receptors; B₂, bradykinin receptor; TNFR, tumor necrosis alpha receptor; LTR, leukotriene receptor; ECE, endothelin-converting enzyme; bET-1, big endothelin-1; ET-1, endothelin-1; eNOS, endothelial nitric oxide synthase; L-Arg, L-arginine; COX-1, cyclooxygenase 1; CYP450, cytochrome P450 epoxygenase; ACE, angiotensin-converting enzyme; AI, angiotensin I; AII; angiotensin II; AT₁, angiotensin type 1 receptor; AT₂, angiotensin type 2 receptor; ET_A, endothelin type A receptor; ET_B, endothelin type B receptor; PG, prostaglandins; AA, arachidonic acid; EDHF, endothelium-derived hyperpolarizing factor; VGCC, voltage-gated calcium channels; IP, prostacyclin receptor; EETs, epoxyeicosatrienoic acids; HETEs, hydroxyeicosatetraenoic acids; α₁, α₁-adrenergic receptor; α₂, α₂-adrenergic receptor; β₂, β₂-adrenergic receptor; ACh, acetylcholine; NE, norepinephrine; NPY, neuropeptide Y; P1, purinergic type 1 receptor; Y₁, neuropeptide Y receptor; IL, interleukin-6 receptor; CGRP, calcitonin gene-related peptide; CLR, calcitonin-like receptor.