From what I’ve read it appears that acupuncture leads to ADP compounds may have a vasodilatory by binding to adenosine A1 receoptors and purine receptors. This leads to NO production. NO probably participates in vasocilation induces by acupuncture. The sympathetic nervous system may also be involved because of studies howing dense sympathetic nerve innervation of arterioles, lymphatic vessels and mast cesll.
Activity in sympathetic efferents (as during acupuncture) also mediated the release of NO, supporting the sugestions that both CGRP and NO have important roles in the vasodilatory response.
He goes on to say that, of course, clinical relevance is the most important aspect of all this, and refers to a study on Achilles tendonitis where subjects treated with acupuncture had much lower pain scores than subjects in the exercise group.
From anecdotal, personal experience, I have found patients with Achilles tendonitis and plantar fasciitis respond quite well to acupuncture. Maybe we have CGRP and NO to thank.