A subpopulation of norepinephrine-containing cells in the cat adrenal medulla contain neurotensin (NT) immunoreactive material. Using high performance liquid chromatography (HPLC) and radioimmunoassay with region-specific antisera we have demonstrated that electrical stimulation of the splanchnic nerve releases NT and its metabolites NT(1–8) and NT(1–12) from cat adrenal gland into the circulation. Blood samples from anesthetized cats were simultaneously collected from the adrenolumbar vein and femoral artery over a 10-min period prior to and during splanchnic nerve stimulation. Trains of stimuli (15 Hz/10V) were applied at 30-s intervals over 10 min. Plasma samples were extracted, run on HPLC and column fractions assayed with C- und N-terminal directed antisera. During splanchnic nerve stimulation there was a fivefold increase in NT levels in the adrenolumbar vein while levels in the general circulation remained unchanged. Concomitant with the increase in NT was a two- to threefold increase in the levels of NT(1–8) and NT(1–12). The chromatographic profiles of extracted adrenal glands showed a major peak of immunoreactive material with the same retention time as NT (18.6 ± 3.0 pmol/g weight wet of tissue) as well as a small peaks on NT(1–8) (0.96 ± 0.18 pmol/g) and N(1–12) (2.05 ± 0.1 pmol/g). HPLC analysis of a tryptic digest of the NT-like material gave 1.0 equivalent of NT(1–8) and NT (9–13). These results are consistent with the presence of NT in adrenal tissue and its release and metabolism during stimulation of th