We used solution hybridization to quantify mRNAs for alpha 1A-, alpha 1B-and alpha 1D-adrenoceptor(AR) in rat aortae. The results showed that the mRNA for alpha 1A-, alpha 1B- and alpha 1D-AR was 0.28 +/- 0.03 fmol, 0.35 +/- 0.03 fmol and 0.82 +/- 0.09 fmol, respectively, in 40 micrograms total RNA extracted from rat aorta. The dominant expression of alpha 1D-AR further support the recent findings that alpha 1D-AR is a major functional receptor subtype of AR in rat aorta.