Which of the hormones is secreted by alpha-cells in the pancreas in response to low blood glucose levels?

Glucagon, is a 29-amino acid polypeptide hormone secreted by the -cells of the islets of Langerhans, which plays an impoant role in the regulation of glucose homeostasis by producing antagonistic effects on insulin action. Glucagon release is inhibited by hyperglycemia (high blood glucose levels) and stimulated by hypoglycemia (low blood glucose levels). Ref: Molina P.E. (2010). Chapter 7. Endocrine Pancreas. In P.E. Molina (Ed), Endocrine Physiology, 3e.