[Acute and chronic hypotensive effect of m-nifedipine]

Three groups of adult stroke--prone spontaneously hypertensive rats (SHRsp) were treated with m-nifedipine (m-Nif) 2.5, 5 and 10 mg.kg-1 by intraperitoneal injection. The systolic blood pressure (SBp) decreased significantly. The hypotensive effect persisted for 2-4, 6-8, and 12 h respectively and the peak effect appeared in 1 h. The range of hypotension was markedly greater than that of nifedipine (Nif). In SHPsp, treatment with m-Nif 10 or 30 mg.kg-1.d-1 for 4 weeks reduced significantly the SBp, but the hypotensive action is about the same as Nif.