Noradrenaline and acidic protein(s) in four types of cat carotid body chief cells.

Four types of chief cells can be discerned in the cat carotid body. These cells are referred to as types 1 to 4. They are characterized--in the given order--by decreasing amounts of noradrenaline (argentaffin reaction) and acidic protein(s) (HCl hydrolysis/basic dye methods). The concentrations of acidic protein roughly parallel that of noradrenaline, being highest in type 1 and lowest in type 4 cells. It is suggested that acidic protein and monoamines together are stored in specific granules and secreted by ekcytosis. The various cell types reflect functional conditions. Histochemical methods to identify acidic protein are less sensitive than methods for monamines. Thus, only catecholamines have been detected in chief cells of those animals, which contain only a few and small specific granules. Cat carotid body chief cells, by contrast, serve as a suitable model to demonstrate the parallelism in storage and secretion of monoamines and acidic protein.