Expression of K+-Cl- cotransporters in the alpha-cells of rat endocrine pancreas.
The expression of K+-Cl- cotransporters (KCC) was examined in pancreatic islet cells. mRNA for KCC1, KCC3a, KCC3b and KCC4 were identified by RT-PCR in islets isolated from rat pancreas. In immunocytochemical studies, an antibody specific for KCC1 and KCC4 revealed the expression of KCC protein in alpha-cells, but not pancreatic beta-cells nor delta-cells. A second antibody which does not discriminate among KCC isoforms identified KCC expression in both alpha-cell and beta-cells. Exposure of isolated alpha-cells to hypotonic solutions caused cell swelling was followed by a regulatory volume decrease (RVD). The RVD was blocked by 10 microM [dihydroindenyl-oxy] alkanoic acid (DIOA; a KCC inhibitor). DIOA was without effect on the RVD in beta-cells. NEM (0.2 mM), a KCC activator, caused a significant decrease of alpha-cell volume, which was completely inhibited by DIOA. By contrast, NEM had no effects on beta-cell volume. In conclusion, KCCs are expressed in pancreatic alpha-cells and beta-cells. However, they make a significant contribution to volume homeostasis only in alpha-cells.
Davies
Sarah L
SL
School of Biological Sciences and Department of Medicine, University of Manchester, G.38 Stopford Building, Manchester M13 9PT, UK.
Roussa
Eleni
E
Le Rouzic
Philippe
P
Thévenod
Frank
F
Alper
Seth L
SL
Best
Len
L
Brown
Peter D
PD
D000818:Animals; D048429:Cell Size; D006982:Hypertonic Solutions / Q000494:pharmacology; D007038:Hypotonic Solutions / Q000494:pharmacology; D007515:Islets of Langerhans / Q000737:chemistry* / Q000166:cytology; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D027981:Symporters / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D014018:Tissue Distribution; D000096922:K Cl- Cotransporters
D006982:Hypertonic Solutions; D007038:Hypotonic Solutions; D012333:RNA, Messenger; D027981:Symporters; D000096922:K Cl- Cotransporters; C492281:Slc12a6 protein, rat; C492283:Slc12a7 protein, rat