Cardiac and hemodynamic actions effect of total saponins of Panax notoginseng

On pentobarbital anesthetized open-chest cats iv total saponins of Panaxnotoginseng (PNS) 20mg/kg decreased left ventricular pressure (LVP) 23±9%***, decrased blood pressure (BP) 20±9%***, and decreased total peripheral vascular resistance(TPVR) 24±15%**. Heart rate (HR), left ventricular end diastolic pressure (CVP) did not change significantly. dP/dtmax decreased 20±10%***; t-dP/ dtmax increased 10±5%***. Cardiac stroke work index (LVWI) decreased 21±8%***. Minute tension-time index(TTI/min) decreased 27±15%***. Blood was driven from carotid into femoral artery in cats by a peristaltic pump. PNS iv decreased femoral artery resistance with a lag time just the same as that required to pass through the delay circuit. In dog heart-lung preparation, depressant effect on cardiac pump was observed.(**p<0.05,***p<0.01) To analyse the mechanism of hypotesive action of PNS, the following experiments were performed:1. Fall of BP in spinal cats caused by iv PNS was no less than that in intact anesthetized cats. Fall of BP by intra-vertebral artery injection was not stronger than that by iv route. 2. When the preganglionic fibers of superior cervical ganglion of cats were stimulated, the contraction of the nictitating membrane was not blocked by PNS. 3. The hypotensive effect of PNS was not abolished by propranolol, diphenhydramine or bilateral vagotomy. 4. The pressor effect of epinephrine did not dectease after iv PNS. 5. Direct vasodilation action was observed in blood vessels perfused in vivo (cats) or in vitro (rat hind limbs and rabbit ears). These results suggest that the cause of hypotension is mainly due to direct dilatation of blood vessels by PNS. Depression of myocardial contractility may play a role.