AUTOREGULATION-BLOOD FLOW (BF) TO MUSCLES

SUMMARY

1. The most important factors maintaining BF in skeletal muscle during exercise are the local mechanisms: hypoxia & accumulation of vasodilator metabolites.

2. Some decrease in tonic vasoconstrictor discharge (reduced constrictor tone in the arterioles) may be involved.

3. The ‘muscle pump’ in exercising muscle, improves venous return, lowers venous pressure, & helps increase BF but is not the primary factor in autoregulation.

4. BF in the resting muscle doubles after sympathectomy but once exercise has commenced, there is no difference in flow in normal & sympathectomised muscles.

5. Thus the most important factor increasing BF through an active muscle is local action of metabolites on vessels.

Reference(s)

Barrett, K.E., Barman, S.M., Brooks, H.L., X, J. and Ganong, W.F. (2019). Ganong’s review of medical physiology. 26th ed. New York: Mcgraw-Hill Education