Morales M A, González E, Torres R, Martínez J L
Departamento de Farmacología, Facultad de Medicina, Universidad de Chile, Santiago.
Arch Med Res. 1993 Summer;24(2):177-81.
7-O-demethylisothalicberine (7-O-DI), an alkaloid isolated from Berberis chilensis Gillies ex Hook, induces a negative inotropism and chronotropism on guinea pig isolated atria (IC50 = 1.5 x 10(-4) and 1.8 x 10(-4) M, respectively). As these effects were not antagonized by propranolol, 7-O-DI inhibition of isoproterenol-induced atrial activation seems to be attained through a mechanism distinct of beta-receptor blockade. A probable cholinergic mechanism of action was also ruled out. 7-O-DI atrial effects were completely reversed by a 50% increase of calcium concentration. The spontaneous frequency of rat sinus node was also deeply modified by 7-O-DI, in accordance with previous results obtained in frog cardiac pacemaker cells. It is concluded that 7-O-DI should perform its pharmacological action through calcium entry blockade. These results open expectations for future research about probable therapeutic use for 7-O-DI.
7-O-去甲基异thalicberine（7-O-DI）是一种从智利小檗（Berberis chilensis Gillies ex Hook）中分离出的生物碱，对豚鼠离体心房具有负性肌力和负性变时作用（IC50分别为1.5×10⁻⁴和1.8×10⁻⁴ M）。由于这些作用未被普萘洛尔拮抗，7-O-DI对异丙肾上腺素诱导的心房激活的抑制似乎是通过一种不同于β受体阻断的机制实现的。一种可能的胆碱能作用机制也被排除。钙浓度增加50%可完全逆转7-O-DI对心房的作用。根据先前在青蛙心脏起搏细胞中获得的结果，7-O-DI也可显著改变大鼠窦房结的自发频率。得出的结论是，7-O-DI应通过钙内流阻断来发挥其药理作用。这些结果为7-O-DI可能的治疗用途的未来研究带来了期望。
