Stimulated release of calcitonin gene-related peptide from the human right atrium in patients with and without diabetes mellitus

Calcitonin gene-related peptide (CGRP), a potent vasodilator released during activation from a subset of sensory Aδ- and C-fiber afferents, has been suggested to play a beneficial role in myocardial ischemia. Variations in CGRP release can possibly be correlated with diseases that involve changes in activity or degeneration of cardiac afferent fibers. The aim of the present study was to examine basal and stimulated CGRP release from cardiac tissue in patients who underwent cardiopulmonary bypass surgery and to compare patients with and without known history of diabetes mellitus. Small pieces of the right atrium routinely excised during the bypass operations were passed through series of oxygenated solutions. The TRPV1 receptor agonist capsaicin and the nitric oxide donor NONOate were added for stimulation of cardiac afferent fibers. The eluates were processed using an enzyme immuno-assay (EIA) for measurement of CGRP concentrations. Both capsaicin and NONOate caused significant increases in CGRP release. No significant differences in CGRP release between patients with and without diabetes mellitus were examined. The present study evaluates a simple and reproducible model for measuring stimulated CGRP release from the human right atrium.