Expression of multiple α2-adrenergic receptor messenger rna species in rat tissues

We used a human platelet α2-adrenergic receptor probe to study the tissue distribution and messenger RNA (mRNA) forms of the rat α2-adrenergic receptor. Under stringent conditions of hybridization and washing, we detected an mRNA species of 3.8 kb. The abundance of this form follows the order spleen, kidney, brain stem and cortex, and skeletal muscle and lung and is consistent with the reported abundance and tissue distribution of the receptor activity. A 3.0 kb mRNA form was also detected in cerebral cortex and brain stem and a 4.1 kb mRNA form was observed in kidney under less stringent hybridization conditions. The tissue distribution of the 3.0 kb form is different from that of α1,-and β-adrenergic receptors and the D2 dopaminergic receptor. The mRNA analysis combined with Southern blot analysis of rat and human genomic DNA indicate that: 1) in addition to a 3.8 kb rat os-adrenergic receptor transcript, there are other mRNA forms in the rat that do not correspond to previously described adrenergic receptor mRNA species and 2) more tban one α2-adrenergic receptor gene in the rat Is expressed in a tissue-specific manner. © 1990 American Heart Association, Inc.