The expression of mRNA for K⁺-Cl^– cotransporters (KCC) was examined in rat pancreas.

Rats were killed humanely by an overdose of halothane anaesthetic. RNA was extracted either from whole pancreas (endocrine and exocrine tissue), or from isolated islets (prepared by collagenase digestion, see Miley et al. 1997). RT-PCR was performed using specific primers for all of the KCC isoforms (i.e. KCC1, KCC2, KCC3a, KCC3b and KCC4). Products were characterised by nucleotide sequencing.

PCR products, of the appropriate size, were obtained with the primers for KCC1, KCC3b and KCC4 and mRNA isolated from the whole pancreas. Products were obtained neither with primers for KCC2 (neuronal specific isoform) nor with primers for KCC3a. PCR performed on islet mRNA revealed expression of KCC3a, KCC3b and KCC4. The products obtained showed 95 %, 100 % and 96 % identity to the known sequences of KCC3a, KCC3b and KCC4, respectively. Neither mRNA for KCC1 nor mRNA for KCC2 was determined in the islets.

In conclusion, we have provided evidence for the expression of KCC3a, KCC3b and KCC4 mRNA in rat pancreatic islets. KCC1 appears to be expressed in the exocrine pancreas but not in the endocrine pancreas.

S.L.D. is supported by a MRC Studentship.