Nutritive blood flow as an essential element supporting muscle anabolism.
OBJECTIVE
Much of the recent literature concerning hormonal effects on muscle assumes that full perfusion occurs at all times such that nutrient and hormone delivery is complete. New methods to measure the extent of nutritive blood flow in muscle show that this is not the case and that anabolic hormones such as insulin increase nutritive flow and that other agents that increase bulk flow have little effect. This review examines the latest developments concerning insulin action to increase nutritive perfusion of muscle and agents that interact with this effect and which could potentially modulate anabolism.


RESULTS
We examine recent attempts to define the anatomical nature of non-nutritive flow route in muscle, the quick onset of insulin action to recruit nutritive blood flow at doses lower than that which activates glucose uptake and bulk blood flow, actions of the inflammatory cytokine tumour necrosis factor alpha TNFalpha to oppose physiologic insulin action, interfibrillar fat depots that grow on the non-nutritive vasculature of muscle and underpin a 'vascrine hypothesis', and drugs that reduce insulin resistance by ameliorating vascular dysfunction.


CONCLUSIONS
Recognition that nutrient and hormone delivery to muscle is controlled by microvascular perfusion and not necessarily by bulk blood flow is the key issue.
Clark
Michael G
MG
University of Tasmania, Hobart, Australia. Michael.Clark@utas.edu.au
Rattigan
Stephen
S
Barrett
Eugene J
EJ
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000378:metabolism*; D012039:Regional Blood Flow / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000502:physiology
D001786:Blood Glucose; D007328:Insulin; D014409:Tumor Necrosis Factor-alpha