The antiadrenergic actions of amiodarone (Am) are well known but its effect and that of its metabolite, desethylamiodarone (DAm), on beta-receptor density (Bmax) and affinity (KD) are poorly defined. Thus, the acute and chronic effects of Am and DAm on myocardial beta-receptors in rabbits were determined relative to changes in thyroid hormones and serum and tissue drug concentrations. Bmax and KD were measured by radio-ligand binding, thyroid hormones by RIA, and drug levels by HPLC. Compared with controls, intravenous Am (20 mg/kg) reduced Bmax by 23% (p less than 0.05) and DAm (20 mg/kg) by 32% (p less than 0.05). After 3 weeks of chronic drug, the corresponding value for Am was 24% (p less than 0.05) versus 45% (p less than 0.05) for DAm. The effect of DAm was significantly greater (p less than 0.05) than that of Am, being comparable to that of Am (-44%) after 6 weeks. In the case of Am, doubling the dose (and myocardial level) led to no further decrease in Bmax. DAm also reduced Bmax more following chronic treatment than after acute administration (-45 versus -32%), a difference of borderline significance. Following 3 weeks of p.o. Am, T3 decreased 3% (NS) and reverse T3 (rT3) increased 90% (p less than 0.05); after 6 weeks, the corresponding values were 25% (p less than 0.05) and 181% (p less than 0.01). After 1 week of p.o. DAm, T3 did not change but rT3 increased by 34% (p less than 0.05); after 3 weeks the corresponding values were 21% (p less than 0.01) and 64% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

译文

胺碘酮 (Am) 的抗肾上腺素作用是众所周知的,但其作用及其代谢物去乙基胺碘酮 (DAm) 对 β 受体密度 (Bmax) 和亲和力 (KD) 的作用尚不明确。因此,相对于甲状腺激素以及血清和组织药物浓度的变化,确定了Am和DAm对兔心肌 β 受体的急性和慢性影响。通过放射配体结合测量Bmax和KD,通过RIA测量甲状腺激素,通过HPLC测量药物水平。与对照组相比,静脉内Am (20 mg/kg) 将Bmax降低23% (p小于0.05),将DAm (20 mg/kg) 降低32% (p小于0.05)。慢性用药3周后,Am的相应值为24% (p小于0.05),而DAm的相应值为45% (p小于0.05)。大坝的效果明显大于Am (p小于0.05),6周后与Am (-44%) 相当。在Am的情况下,剂量 (和心肌水平) 加倍导致Bmax没有进一步降低。与急性给药 (-45对-32%) 相比,长期治疗后DAm还降低了Bmax,这具有临界意义。经过3周的p.o.Am、T3下降3% (NS) 和反向T3 (rT3) 上升90% (p小于0.05); 6周后,相应值分别为25% (p小于0.05) 和181% (p小于0.01)。一周后的p.o.DAm,T3没有变化,但rT3增加了34% (p小于0.05); 3周后相应的值分别为21% (p小于0.01) 和64% (p小于0.01)。(摘要截断在250个单词处)

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