The ability of ATP-free granule material from bovine adrenal medulla to bind inorganic cations and biogenic amines.

Bovine adrenal medullary granules isolated by millipore filtration were depleted of CA and ATP by dialysis. The resulting material showed an ability to bind inorganic cations and biogenic amines in a concentration-dependent manner. The similarity of the uptake curves, the identical uptake maxima and the narrow pH range (between 4-7) over which the uptake of the inorganic and organic cations took place indicated a binding of these ions to common sites. In addition, the fact that all the uptake curves fitted the Rothmund-Kornfeld equation for cation exchangers corroborated the cation exchanger properties of the dialyzed granule material. The CA binding capacity corresponded to 20-30% of the normal CA content of bovine medullary granules.