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四氢小檗碱为四氢原小檗碱同类物,但四氢原小檗碱同类物的降压和抗心律失常的作用机理尚待阐明。本文应用放射配基结合试验和离体猪冠状动脉环研究THB对β-肾上腺素受体的作用。结果表明,THB能竞争[~3H]DHA和兔肺细胞膜的结合部位,其Ki值为2.7±0.4μmol/L;Pro能拮抗NE对猪冠状动脉的扩张,NE的pD_2值为6.3±0.2,Pro的pA_2为8.8±0.2,THB的作用与Pro既相似又有区别,表现为NE的对数浓度反应曲线右移又压低的双重拮抗作用,其pA_2为7.7±1.3,pD_2值为5.1±0.2。以上结果提示,THB为β肾上腺素受体拮抗剂,此外,它对其它受体也可能有亲和力。
Tetrahydroberberine is a tetrahydroprotoberberine analog, but the mechanism of antihypertensive and antiarrhythmic actions of tetrahydrobiopterin analogs remains to be elucidated. In this paper, radioligand binding assay and in vitro porcine coronary artery rings were used to study the effect of THB on β-adrenergic receptors. The results showed that THB could compete with the binding sites of [~ 3H] DHA and the rabbit lung cell membrane with a Ki value of 2.7 ± 0.4 μmol / L. Pro could antagonize the expansion of porcine coronary arteries by NE. The pD_2 value of NE was 6.3 ± 0.2, The pA_2 of Pro was 8.8 ± 0.2. The effect of THB was similar to and different from that of Pro, showing a double antagonistic effect of rightward and downregulation of logarithmic concentration of NE with pA_2 of 7.7 ± 1.3 and pD_2 of 5.1 ± 0.2 . The above results suggest that THB is a beta-adrenergic receptor antagonist, in addition, it may also have affinity for other receptors.