Mechanistn. of insulin secretion

Abstract

Abstract Insulin release in vivo is regulated principally by the circulating glucose level together with extensive modulatory effects exerted by hormones, neurotransmitters, and other nutrients. The main agents capable of influencing insulin release, both physiologically and experimentally, are summarized in Fig. 1. These include initiators of secretion, such as metabolic substrates and the sulphonylureas, and a variety of substances that act to potentiate or inhibit the secretory response to an initiator. Of major importance are paracrine influences from adjacent non-[3-cells of the islet; these include glucagon, released from a-cells, and somatostatin, released from D-cells. Both neural inputs and gastrointestinal hormones may underlie the enhanced secretory response to oral, as opposed to intravenous, glucose loading. Pharmacological agents, in particular the sulphonylureas, also influence insulin secretion.