[Comparative effects of Panax notoginseng saponins, verapamil, and norepinephrine on cerebral circulation in anesthetized rats and rabbits].

In urethane-anesthetized New Zealand rabbits, mean blood pressure (MBP) and cerebrovascular resistance (CVR) fell by 27-47% and 11-17% (P < 0.05), respectively after Panax notoginseng saponins (PNS) 20-80 mg.kg-1 i.v. Verapamil (Ver) 30 micrograms.kg-1 i.v. showed similar effects, but norepinephrine (NE) 30 micrograms.kg-1 i.v. showed opposite effects. PNS and Ver reduced the MBP and CVR in sodium pentobarbital-anesthetized Wistar rats. The actions of PNS and Ver on cerebral blood flow (CBF) were related to the animal species, i.e. PNS increased CBF in rats but reduced that in rabbits, Ver increased CBF in rabbits but had no effects on that in rats. In isolated ring segments of New Zealand rabbit basilar arteries, PNS 1 and 3 mg.ml-1 non-competitively inhibited the contractions induced by KCl with the pD2' value 2.69 +/- 0.20 (-lg g.ml-1). The results indicate that PNS and Ver are vasodilators of brain blood vessel, which would be beneficial to cerebral circulation, while NE is a vasoconstrictor of brain blood vessel.