Release of calcitonin gene-related peptide (CGRP) from capsaicin-sensitive vasodilator nerves in the rat mesenteric artery.

The effect of perivascular nerve stimulation (PNS) and capsaicin treatment on the release of calcitonin gene-related peptide (CGRP) was examined by radioimmunoassay (RIA) in isolated, perfused rat mesenteric arteries. In the preparation precontracted by methoxamine and treated with guanethidine, an adrenergic neuron blocker, PNS and capsaicin induced vasodilator responses and increase of CGRP-like immunoreactivity (CGRP-LI) in the perfusate in a frequency-dependent manner. The CGRP-LI released by capsaicin was identified as CGRP and its oxidized form by high-performance liquid chromatography coupled with RIA. After the tissue was treated with capsaicin, PNS didn't cause both the vasodilator response and the increase of CGRP-LI in the perfusate. These findings suggest that CGRP plays a neurotransmitter role in capsaicin-sensitive vasodilator nerves in rat mesenteric arteries.