de Carvalho J E, Lapa A J
Department of Pharmacology, Natural Products Section, Escola Paulista de Medicina, Sao Paulo, Brazil.
J Ethnopharmacol. 1990 Aug;30(1):43-54. doi: 10.1016/0378-8741(90)90016-m.
The powdered bark of Maquira sclerophylla is consumed as snuff in north Brazil. Both the crude and the purified hydrosoluble extract (WP) injected i.p. in the dose range of 0.05-0.5 g/kg induced hyperexcitability, tremors, motor incoordination, ataxia, quietness and muscle relaxation in rats. The effects were progressive, dose-related and reversed after 30 min. Anesthetized rats, guinea-pigs and dogs injected with the purified extract (10-50 mg/kg, i.v.) showed a biphasic change of carotid blood pressure. The early and transient hypotension was blocked by atropine but not by vagotomy: the secondary hypertension was long lasting and sustained for over 30 min. The hypertension was shortened but not blocked after ganglionic blockade or reserpine treatment. Either pithing or alpha receptor blockade with yohimbine reduced both effects of the extract. Guinea-pigs and dogs were more responsive than rats and died by heart arrest. Incubation of WP (20 micrograms/ml) increased both the rate and force of contraction of isolated guinea-pig right atria by 2 and 5 times, respectively. Propranolol (4 micrograms/ml) blocked the chronotropic effect but did not decrease the inotropic effect. In electrically driven guinea-pig left atria, WP (10 micrograms/ml) increased the force of contraction by 80% and the maximum rate of force development by 60%, but did not change the time to peak tension, the time to 50% relaxation, or the rate of relaxation. These cardiovascular effects resemble those of digitalis-like drugs. Cardenolides were detected in WP by phytochemical screening.
在巴西北部，人们将硬叶马基拉树的树皮粉末当作鼻烟使用。粗制和纯化的水溶性提取物（WP）腹腔注射给药，剂量范围为0.05 - 0.5 g/kg时，可引起大鼠过度兴奋、震颤、运动不协调、共济失调、安静和肌肉松弛。这些作用呈进行性、剂量依赖性，30分钟后可逆转。给麻醉的大鼠、豚鼠和狗静脉注射纯化提取物（10 - 50 mg/kg）后，颈动脉血压出现双相变化。早期短暂性低血压可被阿托品阻断，但不能被迷走神经切断术阻断；继发性高血压持续时间长，可持续30分钟以上。神经节阻断或利血平治疗后，高血压持续时间缩短但未被阻断。用育亨宾进行脊髓毁损或α受体阻断均可降低提取物的两种作用。豚鼠和狗比大鼠更敏感，可因心脏骤停死亡。WP（20微克/毫升）孵育可使离体豚鼠右心房的收缩速率和收缩力分别增加2倍和5倍。普萘洛尔（4微克/毫升）可阻断变时作用，但不降低变力作用。在电驱动的豚鼠左心房中，WP（10微克/毫升）可使收缩力增加80%，最大力发展速率增加60%，但不改变达到峰值张力的时间、50%舒张时间或舒张速率。这些心血管作用类似于洋地黄样药物。通过植物化学筛选在WP中检测到了强心苷。
