Chromogranin A (CgA) and its processed, bioactive peptides are known effectors numerous biological pathways. Initially, CgA was studied as an important prohormone peptide of the chromaffin cells of the adrenal gland. Previous studies have shown CgA's necessity in the exocytosis and the release of peptides stored within dense -core secretory granules. Catestatin is a product of CgA processing and serves as a major inhibitor of CgA by antagonizing CgA's effects. This thesis investigated the expression of CgA and catestatin in tissues outside the adrenal gland. We were particularly interested in the tissues outside the adrenal medulla that incur collateral damage as a result of increased sympathetic tone. Specifically, we investigated the processing and expression of chromogranin A into its inhibitory peptide, catestatin in the heart and brain. We found not only a differential processing pattern between the adrenal, heart, and brain tissue, but also an age-dependent processing patter
