text: The influence of << (+/-)-tamsulosin >>, a selective [[ alpha 1A-adrenoceptor ]] antagonist, on the positive inotropic effect and the accumulation of inositol phosphates that are induced via alpha 1-adrenoceptors was studied in comparison with that of another alpha 1A-adrenoceptor ligand oxymetazoline in the rabbit ventricular myocardium.