QUANTIFICATION AND DISTRIBUTION OF ALPHA(1)-ADRENOCEPTOR SUBTYPE MESSENGER-RNAS IN HUMAN PROXIMAL URETHRA

1 We performed RNase protection assays and in situ hybridization to in vestigate the ratio of the three alpha(1)-adrenoceptor subtype mRNAs, alpha 1a, alpha 1b and alpha 1d, in human proximal urethra, and their localization in urethral cross-sections. As revealed by the RNase prot ection assays, alpha 1a was the predominant subtype mRNA in both male and female urethral samples. alpha 1d mRNA was detected only in the fe male sample, and crib mRNA was not detected in any of the samples test ed. The ratio of the abundance of the subtype mRNAs, alpha 1a: alpha 1 b:alpha 1d, was 100:0:0 in the male urethra and 90:0:10 in the female urethra. 2 In situ hybridization studies showed no significant differe nces in the cross-sectional distribution of alpha(1)-adrenoceptor subt ype mRNAs between male and female urethras. Intense alpha 1a staining was observed in the smooth muscle of the urethra, but alpha 1b and alp ha 1d staining was much less intense. 3 Of the three cloned alpha 1 su btypes, alpha 1a is the most likely to be responsible for the contract ion of the human urethra. Owing to the side effects of nonselective al pha 1 drugs, alpha(1)-selective drugs may be clinically superior to no nselective drugs for the treatment of urethral disorders.