In vivo and in vitro ACTH response to ovine corticotropin-releasing factor in a bronchial carcinoid from a patient with ectopic ACTH syndrome.

ACTH response in vivo and 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, 1 microgram/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(-8) and 10(-7) M of o-CRF significantly stimulated ACTH release in cultured bronchial carcinoid cells.