Dorsal root vasodilatation in cat skeletal muscle

Area of Science:

• Neuroscience
• Physiology
• Pharmacology

Background:

• Skeletal muscle blood flow regulation is complex.
• Afferent nerve fibers play a role in modulating muscle hemodynamics.

Purpose of the Study:

• To investigate the effects of antidromic stimulation of dorsal roots L6-S1 on gastrocnemius muscle blood flow in cats.
• To determine the role of prostaglandins in mediating this response.

Main Methods:

• Antidromic stimulation of dorsal roots L6-S1 in chloralose-anesthetized cats.
• Measurement of muscle vascular conductance.
• Administration of prostaglandin synthetase inhibitors (indomethacin, acetylsalicylic acid), guanethidine, and atropine.
• Comparison with acetylcholine-induced and functional hyperemia.

Main Results:

• Antidromic stimulation of small afferent fibers increased muscle vascular conductance by 50-60%.
• This vasodilation was slow to onset and long-lasting.
• The response was unaffected by guanethidine or atropine but significantly reduced by prostaglandin synthetase inhibitors.

Conclusions:

• Activity in small myelinated or unmyelinated afferent fibers of skeletal muscle increases muscle blood flow.
• This increase in blood flow is, at least partly, mediated by locally synthesized prostaglandins.