Phorbol myristate acetate: effect of a tumor promoter on insulin release from isolated rat islets of Langerhans.

Phorbol myristate acetate (PMA), a tumor-promoter capable of influencing biologic functions of many cell systems, has been demonstrated to augment glucose-initiated insulin release from isolated rat islets of Langerhans. PMA caused a 2-fold increase in insulin release. This effect of PMA did not alter the sigmoidal relationship of insulin released to glucose concentration. The effect of PMA on insulin secretion from the islet beta-cells persists and a challenge with glucose alone, subsequent to a pulse of PMA, elicits an augmented insulin release response.