Volume-sensitive amino acid efflux from a pancreatic beta-cell line

• Published in: Molecular and cellular endocrinology Vol. 162; no. 1-2; pp. 203 - 210
• Main Authors: Grant, A C, Thomson, J, Zammit, V A, Shennan, D B
• Format: Journal Article
• Language: English
• Published: Ireland 25-04-2000
• Subjects: 4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid - pharmacology; Amino Acids - metabolism; Animals; Aspartic Acid - metabolism; Biological Transport, Active - drug effects; Cell Size; Islets of Langerhans - cytology; Islets of Langerhans - drug effects; Islets of Langerhans - metabolism; Osmotic Pressure; Rats; Taurine - metabolism
• ISSN: 0303-7207

Cell swelling, induced by a hyposmotic shock, increased the fractional release of taurine from INS-1 cells. Volume-sensitive taurine release was (a) dependent upon the extent of cell swelling; (b) fully reversible; and (c) temperature dependent. Volume-sensitive taurine efflux was independent from the trans-membrane Na(+)-gradient. DIDS markedly inhibited volume-activated taurine efflux but not basal taurine release suggesting that the volume-sensitive pathway is quiescent under isosmotic conditions. Volume-activated taurine release inactivated in the continued presence of a hyposmotic shock. Cell-swelling also increased the fractional release of D-aspartate from INS-1 cells. Volume-activated D-aspartate efflux was inhibited by DIDS, albeit to a lesser extent than volume-sensitive taurine release. It is predicted that volume-sensitive amino acid efflux acts in parallel with other volume-activated transport mechanisms to regulate the volume of insulin-secreting cells.