HCO 3--dependent volume regulation in alpha-cells of the rat endocrine pancreas.
Ion transport activity in pancreatic alpha-cells was assessed by studying cell volume regulation in response to anisotonic solutions. Cell volume was measured by a video imaging method, and cells were superfused with either 4-(2-hydroxyethyl)piperazine-1-ethanesulfonic acid-buffered or HCO(3)(-) -buffered solutions. alpha-Cells did not exhibit a regulatory volume increase (RVI) in response to cell shrinkage caused by hypertonic solutions. A RVI was observed, however, in cells that had first undergone a regulatory volume decrease (RVD), but only in HCO(3)(-)-buffered solutions. RVI was also observed in response to a HCO(3)(-) -buffered hypertonic solution in which the glucose concentration was increased from 4 to 20 mM. The post-RVD RVI and the glucose-induced RVI were both inhibited by 10 microM 5-(N-methyl-N-isobutyl) amiloride or 100 microM 2,2'-(1,2-ethenediyl) bis (5-isothio-cyanatobenzenesulfonic acid), but not by 10 microM benzamil nor 10 microM bumetanide. These data suggest that Na(+)-H(+) exchangers and Cl(-)-HCO(3)(-) exchangers contribute to volume regulation in alpha-cells.
Davies
Sarah L
SL
Faculty of Life Sciences, University of Manchester, Second Floor CTF Building, Manchester, M13 9NT, UK.
Best
Len
L
Brown
Peter D
PD
D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology*; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D050416:Glucagon-Secreting Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014882:Water-Electrolyte Balance / Q000187:drug effects / Q000502:physiology*
D001639:Bicarbonates