异钩藤碱的降压及血流动力学作用(英文)

Hypotensive and hemodynamic effects of isorhynchophylline in conscious rats and anaesthetized dogs

在清醒正常血压大鼠,iv Isorhy2.5 mg/kg对BP及HR均无明显影响,iv5 mg/kg则使DAP和HR降低,但SAP无变化,剂量加大至10 mg/kg时,上述各项指标均明显降低。经十二指肠内给Isorhy10 mg/kg后20 min出现BP及HR降低,而20mg/kg剂量组于10 min开始出现BP及HR的进一步下降.Isorhy(10mg/kg和2 mg/kg,iv)亦能分别降低肾性高血压清醒大鼠和麻醉犬的BP。icv表明中枢不是降压作用的主要部位,在体条件下无α-受体和神经节阻断作用。Isorhy使清醒大鼠和麻醉犬的LVSP,dP/dt_(max),V_(max)等左室收缩性能指标短暂下降,而BP呈持久性降低。在麻醉犬给药后CO,CI,HR及LVWI下降的同时SV和SI不变,TPVR降低,反映心肌氧耗的TTI明显减少.结果提示Isorhy具有肯定的降压作用,其持续降压与扩张血管及减慢心率导致CO下降有关,而其负性肌力作用亦可能参与了早期的降压机理.Isorhy能减少心肌氧耗对高血压心肌劳损可能有保护意义。

The hypotcnsive effect of iso-rhynchophylline(Isorhy)was studied in conscious rats and anaesthetized dogs.Isorhy in dose of 2.5mg/kg was not effective on BP and HR; it(5 mg/kg,iv)lowered DAP and HR,but not SAP statistically; in dose of 10 mg/kg(iv),a marked decrease in SAP,DAP and HR was observed.Isorhy administered by duodenum at doses of 10 mg/kg and 20 mg/kg produced a hypotensive effect at 20 min and 10 min respectively after medication,and the effects lasted for more than 3 h.The BP and HR were also reduced by Isorhy(10 mg/kg and 2 mg/kg,iv respectively)in hypertensive rats and anaesthetized dogs.The fall in BP was not observed by intra-cercbroventricular injection(icv)0.2 mg/kgof Isorhy,and a transient hypotensive effect was observed by icv dose of 0.4 mg/kg.The hemo-dyhamic effects of Isorhy in conscious rats and anaesthetized dogs have shown that Isorhy produced a transient reduction of LVSP,dP/dtmax and Vmax At this time,the BP was reduced persistently.In anaesthetized dogs,TPVR,CO,HR,CI and LVWI were decreased,but no significant changes of SV and SI were observed.The TTI which indicated myo-cardial oxygen consumption was reduced markedly.Results suggest that the BP could be decreased by Isorhy markedly,whereas the persistent hypotensive effect was mainly due to both of the reduction in TPVR and CO induced by lowered HR.However,the effect of transient inhibition of myocardial contractility plays a hypotensive role in the initial phase of action.The decrease of myocardial oxygen consumption would protect the heart against ischemia induced by hypertension.