Abstract: AIM: To observe the effects of BWYJ on blood pressure (BP) in the normal-tensive, hypertensive rats and haemodynamics in cats.METHODS: The BP of the normal-tensive and renal hypertensive rats was measured and hemodynamics parameters were recorded in thoractomic cats.The effects of BWYJ on cardiovascular center and ganglia were observed.RESULTS: In normaltensive and hypertensive rats, BWYJ of 1.2 and 2.4 mg·kg^-1 (iv) decreased SAP and DAP in normal-tension rats.BWYJ at oral doses of 10, 20 and 40 mg·kg^-1 had a hypotensiove effect with little influence in heart rate.In hypertensive rats, the hypotensive effect of BWYJ were in a dose-dependent manner at oral doses of 5, 10 and 20 mg·kg^-1.BWYJ 2.5 mg·kg^-1 by duodenum produced a reduction of DAP, TPR and LVWI.BWYJ 5.0 mg·kg^-1 produced a reduction of SAP, DAP, LVSP,±dp dtmax and TPR.The drop in BP was not observed by icv BWYJ.The contraction of third eyelid induced by the stimulation of preganglionic fibre of superior cervical nerve ganglia was not effected by BWYJ.CONCLUSION: BWYJ may decrease the blood pressure in the renal hypertensive and normal-tensive rats.The hypotensive effect of BWYJ is mainly due to vasodilating and declining perpheral resistance, and the inhibition of myocardial contractility might play a hypotensive role.

Key words: naftopidil BWYJ, hypertensial rat, blood pressure(BP), hemodynamics