Evidence for an adrenal contribution to plasma digitalis-like factors

Digitalis-like factors (DLF) were assayed on plasma collected serially using antibody to digoxin: (1) after intravenous ACTH (n = 3 patients) and (2) after 0.15 U/kg crystalline insulin, 50 micrograms gonadotropin-releasing hormone and 0.2 mg thyrotropin-releasing hormone (n = 7) as a combined pituitary function test. Patients had either hypothalamic-pituitary or ovarian problems. Mean values for DLF rose fourfold after ACTH, and by a factor of 2.3 with the combined pituitary function test. DLF rose at least 50% in all 10 subjects. In 3 dogs, adrenal vein values for DLF were on average more than double values in either adrenal artery or lower vena cava. These results suggest that certain DLFs have an adrenal origin.