Differential expression of alpha(2)-adrenoceptor subtypes in purified rat pancreatic islet A- and B-cells

In the endocrine pancreas, alpha(2)-adrenoceptor stimulation reduces glucose-induced insulin secretion from islet B-cells. There is, however, controversy with regard to the effects of alpha(2)-agonists on islet A-cell function. In this paper, we have used RNA samples prepared from whole rat islets and from FACS-purified rat A- and B-cells to study alpha(2)-adrenoceptor subtype expression. RNase protection assays detected transcripts encoding alpha(2a), and alpha(2b) subtypes in the RNA pool of rat islets. Reverse transcription-PCR revealed that transcripts for all three alpha(2a)-adrenoceptor subtypes are present in rat islet cells and in purified A-cell RNA. In contrast, RT-PCR of islet B-cell RNA yielded products corresponding to alpha(2a) and alpha(2c), with no evidence for the presence of alpha(2b). Thus, the results reveal that both islet cell types express more than one receptor subtype and suggest that the distribution of the subtypes may differ between rat islet A- and B-cells. Copyright (C) 1997 Elsevier Science Inc.