An osmotic-sensitive taurine pool is localized in rat pancreatic islet cells containing glucagon and somatostatin

• Published in: American journal of physiology: endocrinology and metabolism Vol. 281; no. 6; pp. E1275 - E1285
• Main Authors: Bustamante, J, Lobo, M. V. T, Alonso, F. J, Mukala, N.-T. A, Gine, E, Solis, J. M, Tamarit-Rodriguez, J, Martin Del Rio, R
• Format: Journal Article
• Language: English
• Published: United States 01.12.2001
• Subjects: Amino Acids - metabolism; Animals; Glucagon - metabolism; Immunohistochemistry; In Vitro Techniques; Insulin - metabolism; Islets of Langerhans - metabolism; Islets of Langerhans - ultrastructure; Male; Microscopy, Electron; Osmolar Concentration; Perfusion; Rats; Rats, Wistar; Somatostatin - metabolism; Taurine - metabolism
• ISSN: 0193-1849; 1522-1555
• DOI: 10.1152/ajpendo.2001.281.6.E1275

Departments of 1  Physiology and 2  Biochemistry, Faculty of Medicine, Universidad Complutense, 28040 Madrid; and 3  Department of Investigation, Hospital Ramón y Cajal, 28034 Madrid, Spain Previous reports have dealt with the hypoglycemic properties of taurine and its effects on insulin secretion by adult and fetal isolated islets. We have studied the presence and cellular distribution of taurine in rat islets, the conditions to evoke its release, and its possible modulatory action on insulin secretion. We localized taurine by techniques of double immunolabeling in most glucagon-positive cells and in some somatostatin-positive cells, whereas insulin-positive cells were not labeled with the taurine antibody. Although high-glucose stimulation did not evoke any taurine release, a hyposmotic solution (17% osmolarity reduction) induced a specific phasic release of taurine and GABA (34 and 52% increase on their basal release rate). On the other hand, taurine (10 mmol/l) application slightly reduced the second phase of insulin secretion induced by glucose stimulation. In conclusion, taurine is highly concentrated in glucagon-containing cells of the islet periphery. It is not liberated by glucose stimulation but is strongly released under hyposmotic conditions. All of these data suggest that taurine plays an osmoregulatory role in -cells. taurine distribution; -aminobutyric acid release; amino acid content; insulin secretion; immunocytochemistry