ABSTRACT
The chromaffin vesicle is the characteristic organelle of the adrenal chromaffin cell. This chapter considers the composition of this model secretory vesicle and then the characterizations of other aspects of the chromaffin cell. The most significant constituents of the adrenal chromaffin vesicle are the catecholamines–epinephrine, norepinephrine, and dopamine—generally in that order of concentration. The distribution of chromogranins within the body and in different organisms has been the subject of intense investigations. Chromogranin immunoreactivity was found in gonadotrophs, thyrotrophs, and corticotrophs but not in mammotrophs and somatotrophs. Choline and ethanolamine phosphatides were predominant; the level of lyso compounds was very low. The amount of cholesterol and the cholesterol/phospholipid molar ratio were low compared to those in the other subcellular fractions of chromaffin cells. A complex pattern of neutral glycolipids was observed in contrast to the pattern of gangliosides. Radioimmunoassay and immunohistochemical experiments clearly demonstrated that the peptide is confined to the adrenal medulla.
