To investigate the relationship between skeletal muscle metabolism and arteriolar dilations in the region local to contracting muscle fibers as well as dilations at remote arteriolar regions upstream, we used a microelectrode on cremaster muscle of anesthetized hamsters to stimulate four to five muscle fibers lying approximately perpendicular to and overlapping a transverse arteriole. Before, during, and after muscle contraction, we measured the diameter of the arteriole at the site of muscle fiber overlap (local) and at a remote site ∼1,000 μm upstream. Two minutes of 2-, 4-, or 8-Hz stimulation (5–10 V, 0.4-ms duration) produced a significant dilation locally (8.2 ± 2.0-, 22.5 ± 2.4-, and 30.9 ± 2.1-μm increase, respectively) and at the remote site (4.2 ± 0.8, 11.0 ± 1.1, and 18.9 ± 2.7 μm, respectively). Muscle contraction at 4 Hz initiated a remote dilation that was unaffected by 15-min micropipette application of either 2 μM tetrodotoxin, 0.07% halothane, or 40 μM 18-β-glycyrrhetinic acid between the local and upstream site. Therefore, at the arteriolar level, muscle contraction initiates a robust remote dilation that does not appear to be transmitted via perivascular nerves or gap junctions.
Potassium initiates vasodilatation induced by a single skeletal muscle contraction in hamster cremaster muscle
