A. Majid et al., Expression of the Na+-K+-2Cl(-) cotransporter in alpha and beta cells isolated from the rat pancreas, PFLUG ARCH, 442(4), 2001, pp. 570-576
The expression of the Na+-K+-2Cl(-) cotransporter (NKCCl) in alpha cells an
d beta cells from the rat pancreas was examined. Isolated alpha cells and b
eta cells in a mixed islet cell preparation were identified by volume using
video-imaging methods, and by the expression of glucagon or insulin. The e
xpression of mRNA for NKCCl in pancreatic islets was demonstrated by RT-PCR
. Immunocytochemical studies showed that the NKCCl protein was expressed in
rat beta cells, but not alpha cells. The activity of Na+-K+-2Cl(-) cotrans
porter was also examined, by studying cell volume regulation in response to
HEPES-buffered, hypertonic solutions. A regulatory volume increase was obs
erved in the beta cells but not the alpha cells. It is concluded that the N
KCCl is expressed in rat pancreatic beta cells but not alpha cells. This is
consistent with the hypothesis that Cl- is accumulated above the expected
equilibrium distribution in beta cells, but is below equilibrium in a cells
.