Insulin and intracellular calcium responsiveness to glucagon-like peptide-1 and pituitary adenylate cyclase-activating peptide by dispersed adult porcine islet cells

Background. There is a great need to learn more about porcine islet physiology because porcine islets represent a promising source of xenogeneic tissue for beta-cell replacement therapy in humans. Methods. We evaluated the effects of two important physiological regulators of insulin secretion, glucagon-like peptide-1 (GLP-1) and pituitary adenylate cyclase-activating peptide (PACAP), on insulin release and intracellular calcium ([Ca++](i)) by adult porcine islet cells. Results, Exposure to GLP-1 and PACAP significantly potentiated glucose-induced insulin release and improved the sensitivity to glucose as a secretagogue. About 70% of cells stimulated with 20 mmol/L glucose alone showed an increase in [Ca++](i), whereas the addition of GLP-1 and PACAP induced [Ca++](i) increases in 86% and 93% of cells, respectively. Conclusions. The good insulin and [Ca++](i) responsiveness of porcine islet cells to both GLP-1 and PACAP provides an additional proof of their suitability for transplantation.