Calcium-dependent potassium-stimulated release of neurokinin A and neurokinin B from rat brain regions in vitro.

The release of the tachykinins neurokinin A (NKA) and neurokinin B (NKB) from superfused slices of rat brain was studied. For radioimmunoassay of superfusates and tissue extracts an antiserum which reacts with both NKA and NKB but not with substance P was used. The released immunoreactive material, as well as the immunoreactive material in extracts of the tissue slices, was characterized by cation exchange chromatography and reversed phase high performance liquid chromatography (reversed phase-HPLC). Potassium (50 mM) evoked a calcium-dependent release of tachykinin-like immunoreactivity from slices of frontal cortex and striatum. Reversed phase-HPLC accumbens, striatum and the ventral part of the mesencephalon revealed two major immunoreactive components which co-eluted with synthetic NKA and NKB. Furthermore, the superfusates also contained three minor unidentified immunoreactive components.