Stimulative effect of substance P on insulin secretion from isolated rat islets under normobaric oxygen incubation

The effects of substance P (SP), physalaemin, and [D-Pro2, D-Phe7, D-Trp9]-SP on insulin release from isolated, cultured rat islets were investigated. Substance P stimulated insulin secretion in a dose-dependent manner at 0.1-100 nmol/L under one atmosphere of air with glucose 2.75, 5.5 and 20 mmol/L in the culture medium. Physalaemin 100 nmol/L was added to the culture medium, also stimulated insulin secretion. [D-Pro2, D-Phe7, D-Trp9]-SP 10 nmol/L reversed the stimulative effect of substance P. However, substance P 1 nmol/L inhibited insulin secretion from isolated rat islets under hyperbaric oxygen condations.