In lower concentrations, extra-adrenal chromaffin cells also reside in the bladder wall, prostate, and behind the liver.

In non-mammals, chromaffin cells are found in a variety of places, generally not organised as an individual organ, and may be without innervation, relying only on endocrine or paracrine signals for secretion.

[5][6] Chromaffin cells of the adrenal medulla are innervated by the splanchnic nerve and secrete adrenaline (epinephrine), noradrenaline (norepinephrine), some dopamine, enkephalin and enkephalin-containing peptides, and a few other hormones into the blood stream.

This desensitization and downregulation of α2 adrenergic receptors is caused by the upregulation of the enzyme Adrenal G protein coupled receptor kinase 2 (GRK2) which effectively eliminates the normal autocrine-type negative feedback that normally prevents the cells from over producing the catecholamines and replaces it with a positive feedback loop in which increased secretion further elicits more secretion.

Chromium salts oxidise and polymerise catecholamines to form a brown color, most strongly in the cells secreting noradrenaline.