text: (+)-Tamsulosin, (-)-tamsulosin, << SL 89,0591 >>, Rec 15/2739, SNAP 1069 and RS 17053 appeared to act as competitive antagonists of noradrenaline-mediated contractions of rat aorta yielding pA2 affinity estimates which were similar to binding affinities at cloned [[ human alpha 1D adrenoceptors ]].