In vitro release of somatostatin from cerebral cortical slices: characterization of electrically evoked release

Calcium-dependent, tetrodotoxin (1 microM)-sensitive release of somatostatin-like immunoreactivity (SRIF-LI) could be evoked by electrical field stimulation of vibratome-cut cerebral cortical slices superfused in vitro. The release of SRIF-LI from cortical slices was frequency-dependent, and showed facilitation between 5 and 25 Hz. Release was also current-dependent and above a threshold of 10 mA increased to plateau at 80 mA. Addition of peptidase inhibitors did not improve the recovery of SRIF-LI, and HPLC analysis of the released material showed that over 95% of SRIF-LI released corresponded to SRIF-14 (SRIF-28).