[Pharmacological study of nicergoline. (III). Effects on cerebral and peripheral circulation in animals]

Effects of nicergoline on the cerebral and peripheral circulation were compared with those of dihydroergotoxine (DHE) and papaverine (PAP) in anesthetized and/or immobilized cats. The i.a. injection of nicergoline (0.032 approximately 32 micrograms/kg), similarly to PAP, caused dose-dependent increases in intramaxillary artery (as the human intracarotid artery) blood flow (IMBF) and femoral artery blood flow, but the injection of DHE had no effect on these blood flows. The i.v. injection of nicergoline (32 approximately 128 micrograms/kg) caused a dose-dependent fall in blood pressure (BP) and a transient slight decrease in cerebral vascular resistance, but did not affect IMBF, regional cerebral blood flow (r-CBF), intracranial pressure (ICP) and heart rate (HR). The i.v. injection of DHE produced a slight fall in BP and a marked long-lasting decrease in HR, without affecting other parameters. The i.v. injection of PAP (4 mg/kg) induced marked increases in IMBF, r-CBF, ICP and HR and caused a transient fall followed by a marked elevation in BP. The p.o. administration of nicergoline (0.06 approximately 4 mg/kg) caused a dose-dependent fall in BP and selective inhibition of pressure response to adrenaline (ID50: 0.25 mg/kg). The administration of DHE produced marked inhibition of pressure responses to both adrenaline and noradrenaline, accompanied with a slight fall in BP. Furthermore, the administration of nicergoline (3 approximately 100 mg/kg) induced a dose-dependent fall in BP in SHR. These results suggest that the cerebral and peripheral circulatory effects of nicergoline may be due to direct vasodilating action and alpha-blocking action in the animals.