Expression of the ET_A and ET_B Endothelin Receptor Subtype mRNA in Human Detrusor Cultured Smooth Muscle Cells

Abstract

The aim of this study was to determine the expression of the endothelin receptor subtype mRNAs in human detrusor cultured smooth muscle cells using reverse transcription-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH). First strand cDNA was made from human detrusor cultured smooth muscle cells total RNA and used for PCR with primers designed to amplify fragments of the ET_A and ET_B endothelin receptor subtype cDNA sequences. Subcloned fragments of the ET_A and ET_B endothelin receptor cDNAs were used to synthesize digoxigenin-labeled cRNA probes by in vitro transcription. COS-7 cells transfected with the ET_A and ET_B receptor cDNAs were used as positive control and to confirm the absence of cross-hybridization due to sequence homology. Both ET_A and ET_B receptor mRNAs were detected by RT-PCR analysis. By ISH, both ET_A and ET_B receptor subtype mRNAs were detected. However, ET_A signal was much more intense than ET_B signal. These results indicate that mRNAs for both ET_A and ET_B receptors are expressed in detrusor smooth muscle cells of human urinary bladder. The ET_A receptor is the predominant detrusor ET receptor.

Inward current oscillation underlying tonic contraction caused via ETA receptors in pig detrusor smooth muscle

“…1,24). In the human bladder, Okamoto-Koizumi et al (30) demonstrated the presence of both ET A and ET B receptors and showed that ET A receptors mediate the mechanical response (29,30). However, the underlying mechanisms have not yet been examined even in terms of ionic channels in the plasma membrane.…”