after administration of the ganglionic blocking agents , hexamethonium and atropine , or the selective beta 1-adrenoceptor antagonist , atenolol , the positive inotropic and chronotropic effects of dopexamine hydrochloride were reduced or eliminated , demonstrating that the drug had little or no direct beta 1-adrenoceptor action and that a myocardial beta 2-adrenoceptor action was not involved in its cardiac effects .
C0027061
myocardial
C0018787
cardiac