ABSTRACT
PURPOSE: To know whether the cardiac function of the patients with heart disease is impaired or improved after long-term taking ?-AR antagonists. METHODS: After giving the rats ?-AR selective antagonist, atenolol, for 12wk, the method of radioligand binding assay and the experiment of isolated left-atrium contractive function were carried out to observe the quantity and distribution of ?-AR, its subtypes, ?-AR, and the change of left - atrium contractive function. RESULTS: After long-term administration of atenolol, there were no any obvious changes in ?-AR, the density of the total ?-AR, ?1-AR, and the proportion of ?2-AR in tota1 amount of ?-AR, but the con centrat ion - response cu rves shi fted l e ftwa rd s si gn ifi cant ly as compared with control group- The PA2 value of isoprotenol(ISO) - induced positive inotropic effect after antagonized by ?1-AR selective antagonist CGP20712A in atenolol group was increased significantly as compared with control group. But the PKB value after antagonized by ICI 118511 showed no obvious difference between two groups. HPLC detection showed that the level of plasma atenolol was 3. 5pmol/L in atenolol group and the leveIs of plasma norepinephrine had no significant difference between two groups. But the level of plasma adrenaline in atenolol group was obviously lower than that in control group. CONCLUSIO- N: The long-term administration of ?l-AR antagonist will cause significant increase of the sensitivity of heart ?-AR, especially ?1-AR to excitant ISO. But the number of ?-AR and its subtypes did not change significantly. Besides, after the long-term administration of ?1-AR antagonist atenolol, the level of plasma adrenaline in rats was much lower than that in control group.