ACTH responsein vivoand in vitro to synthetic ovine corticotropin-releasing factor (o-CRF) was examined in a bronchial carcinoid from a patient with ectopic ACTH syndrome. o-CRF, 1μg/kg iv bolus, scarcely increased plasma ACTH or cortisol on one occasion, but they showed a low response on retesting. On the other hand, 10-8and 10-7M of o-CRF significantly stimulated ACTH release in cultured bronchial carcinoid cells.
