Volume-sensitive amino acid efflux from a pancreatic beta-cell line.
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.
Grant
A C
AC
Hannah Research Institute, Scotland, Ayr, UK.
Thomson
J
J
Zammit
V A
VA
Shennan
D B
DB
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001693:Biological Transport, Active / Q000187:drug effects; D048429:Cell Size; D007515:Islets of Langerhans / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D009997:Osmotic Pressure; D051381:Rats; D013654:Taurine / Q000378:metabolism
D000596:Amino Acids; D013654:Taurine; D001224:Aspartic Acid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid