OBJECTIVE: To evaluate the effects of a combination of Yinyanghuo (Herba Epimnedii Brevicornus) (HEB) and Cheqianzi (Semen Plantaginis) (SP) on erectile dysfunction caused by essential hypertension in spontaneously hypertensive rats (SHRs),and to elucidate the role of the angiotensin-converting enzyme 2-angiotensin-(1-7)-Mas receptor (ACE2/Ang[1-7]/Mas receptor) axis in this process.METHODS: A total of 24 SHRs were randomly assigned to three groups: SHR-control,low-dose (12.5 g/kg) and high-dose (25 g/kg) HEB+SP (HEBSP).Eight Wistar-Kyoto rats were used as normal controls.HEBSP was administered by oral gavage for 28 d.Erectile function was measured once a week using the Heaton test.After 4 weeks of treatment,the corpus cavernosum was harvested from each rat to measure nitric oxide (NO),nitric oxide synthase (eNOS) and Ang (1-7) levels,as well as ACE2,Mas receptor and neuronal nitric oxide synthase (nNOS) protein expression.RESULTS: After 4 weeks of treatment,HEBSP significantly increased erectile function in the treated group compared with SHR-control group (P ＜ 0.01).Additionally,HEBSP treatment significantly increased cavernosal levels of Ang (1-7),eNOS and NO.Moreover,HEBSP significantly elevated the expression levels of ACE2,Mas receptor and nNOS.These beneficial effects were elevated in the high-dose HEBSP group.CONCLUSION: HEBSP improved erectile function in SHRs by upregulating the ACE2/Ang (1-7)/Mas receptor axis,eNOS and nNOS pathways.