PC12 cells show immunoreactivity to a number of proteins and peptides, including vasostatin.

N-terminal chromogranin A (CGA) contains peptides with vasoinhibitory properties, called vasostatin I (VST) and II [CGA (1-76) and (1-113) in human and bovine; (1-128) in rat]. Three fragments of VST were synthesized and antisera raised: human CGA (68-76) (VST I) rat CGA (121-128) (VST II fragment 2), and bovine/human CGA (83-91) (VST II, fragment 3). Strong immunoreactivity was observed in PC12 cells with antisera to VST II, fragment 3, VST I, and neuron-specific enolase. Little or no immunoreactivity was observed using antisera to synaptophysin, whole molecule CGA, pancreastatin, protein gene product 9.5, somatostatin, pancreatic polypeptide, or with antibodies 875 and 876 to VST II, fragment 2. Most of the VST antisera cross-reacted, with a species of molecular weight, 61 kDa but one, 874, cross-reacted with two species of molecular weights, 7.2 and 12 kDa. Our results show the presence of N-terminally processed CGA in PC12 cells.