DIFFERENTIAL EXPRESSION OF ALPHA(2)-ADRENOCEPTOR SUBTYPES IN PURIFIEDRAT PANCREATIC-ISLET A-CELL AND B-CELL

In the endocrine pancreas, alpha(2)-adrenoceptor stimulation reduces g lucose-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 fro m whole rat islets and from FACS-purified rat A- and B-cells to study alpha(2)-adrenoceptor subtype expression. RNase protection assays dete cted transcripts encoding alpha(2a), and alpha(2b) subtypes in the RNA pool of rat islets. Reverse transcription-PCR revealed that transcrip ts for all three alpha(2a)-adrenoceptor subtypes are present in rat is let cells and in purified A-cell RNA. In contrast, RT-PCR of islet B-c ell RNA yielded products corresponding to alpha(2a) and alpha(2c), wit h 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 i slet A- and B-cells. Copyright (C) 1997 Elsevier Science Inc.