Dynamics of insulin and glucagon secretion by the isolated perfused cat pancreas

Abstract

1. 1. The dynamics of insulin and glucagon secretion by the isolated perfused cat pancreas was studied in response to glucose and amino acid stimuli. 2. 2. Insulin secretion is biphasic in response to either glucose or amino acid stimuli. 3. 3. Glucose caused a much more pronounced first phase release than did a complete amino acid mixture; whereas glucose and the amino acid mixture stimulated late second phase insulin secretion equipotently. 4. 4. The same amino acid mixture produced a biphasic secretion of glucagon characterized by a rapid and transient spike-release which was followed by a substantial, relatively steady-state, second secretory phase. 5. 5. Various combinations of glucose and amino acids resulted in insulin secretion which suggests a simple additive stimuli phenomenon; whereas no such additive effect was observed with respect to amino acid stimulation of glucagon secretion. 6. 6. Instead, various of the amino acids appear to stimulate maximal glucagon secretion independently. 7. 7. Glucose failed to cause a suppression of amino acid induced glucagon release. 8. 8. The quantitative aspects of this study suggest that the cat pancreas is very responsive to amino acid modulation of hormone release, a fact which may well reflect the high amino acid content of the cat's diet.