Distribution of alpha 1-adrenoceptor subtype mRNAs in human renal cortex

Objective To determine the quantity and distribution of alpha 1-adrenocepto r subtype mRNAs in human renal cortex. Materials and methods Specimens of renal cortex tissue were obtained at the time of radical nephrectomy or total nephroureterectomy from 46 patients ( mean age 59.0 years, SD 14.7) with renal cell carcinoma, renal pelvic or ur eteric tumour. Using the reverse-transcriptase polymerase chain reaction (R T-PCR), the RNase protection assay and in situ hybridization, the presentat ion, quantity and distribution of alpha 1-adrenoceptor subtype mRNAs were d etermined. Results Expression of the three alpha 1-adrenoceptor subtype mRNAs (alpha 1 a, alpha 1b and alpha 1d) was confirmed in the arteries of the renal cortex (arciform, interlobular, arteriole), but among the three subtypes, the alp ha 1b was less apparent by in situ hybridization, Intense alpha 1-mRNA stai ning was apparent especially in the smooth muscle of arterial walls. In bot h proximal and distal renal tubules, each of the alpha 1-mRNAs was less mar ked in cytoplasm than in the arteries. In the glomeruli weak staining was d etected in the endothelium but there was no obvious staining in the veins. RT-PCR showed all three subtypes of alpha 1-adrenoceptor. The RNase protect ion assay showed that the predominant alpha 1-adrenoceptor subtype mRNA in human renal cortex was alpha 1a. However, the abundance of alpha 1a-mRNA in human kidney was much less than in the prostate. Conclusion Three alpha 1-adrenoceptor subtype mRNAs were recognized in huma n renal cortex and detected particularly in the smooth muscle of the arteri es, There was more alpha 1a-adrenoceptor subtype in human renal cortex than the other subtypes. It is not known how each subtype operates against adre nergic stimulation; further studies are needed to examine receptor density or receptor function.