HYPOTENSIVE AND α-ADRENOCEPTOR BLOCKING ACTIONS OF L-TETRAHYDROPALMATINE
Yao Bing, et al (Department of Pharmacology, Xuzhou Medical College, Xuzhou, Jiangsu, China )
Intravenous injection of 1-tetrahydroplamatine ( 1-THP)2.5, 5.0, 10.0 and 20.0 mg/kg lowered the blood Pressure in rats revealed a dose-de-Pendent relationship. The heart rate was slightly slowed along with the lowering of blood Pressure. 1-THP 30 mg/kg iP or 60 mg/kg Po decreased the rat blood Pressure as well. The hypertensive action of NE was antagonized by 1-THP 5.0 mg/kg and its dose-effect curve was shifted to the right, but the Emax of NE was not reduced. 1 -THP 20.0 mg/kg iv reversed the Pres-sor action of adrenaline. These results indicate that 1 -THP can decrease blood Pressure and the machanism may be related to the blocking of α-adre-nocePtors.