Evaluation of mRNAs encoding muscarinic receptor subtypes in human detrusor muscle

Purpose: The present study evaluated the muscarinic receptor subtypes corresponding to m1 to m5 genes in human detrusor muscle. Materials and Methods: The mRNAs encoding m2 and m3 subtypes were assessed by reverse transcription (RT)-polymerase chain reaction (PCR). The amounts of cDNA synthesized from m2 and m3 mRNAs were measured by using subcloned plasmid DNAs. The distribution of m2 and m3 mRNAs in detrusor was estimated by comparing the amount of m2 cDNA with that of m3 cDNA. Results: The m2 mRNA:m3 mRNA ratio was 1.06:1.00 in human detrusor. In the cryostat sections of human detrusor, the presence of both m2 and m3 mRNAs was confirmed by in situ hybridization. However, the RT-PCR products derived from m1, m4 and m5 subtype mRNAs were not detected. Conclusion: These results suggest that human detrusor muscle coexpresses muscarinic m2 and m3 receptors and that the populations of the 2 subtypes are not significantly different.