Chromogranin A: implications for hypertension.

Chromogranin A, the major soluble protein costored and coreleased by exocytosis with catecholamines, has been purified to homogeneity from both bovine adrenomedullary and human phaeochromocytoma chromaffin granules. Each is an acidic monomeric protein. Radio-immunoassays have been established for both bovine and human chromogranin A; the assays detect chromogranin immunoreactivity in adrenergic tissues and subcellular fractions, as well as in serum or plasma. In human plasma, chromogranin immunoreactivity is moderately elevated (mean, 1.5-fold) in essential hypertension, and substantially elevated (mean, 12.5-fold) in subjects with phaeochromocytoma. Initial physiological and pharmacological studies suggest that plasma chromogranin A varies with the state of endogenous exocytotic sympathoadrenal activity, but the plasma chromogranin changes are modest and the ultimate source of the plasma immunoreactivity (e.g. adrenomedullary versus sympathetic neuronal) has not yet been determined.