Spontaneously hypertensive rats (SHR) are characterized by
enhanced nifedipine-sensitive component of sympathetic
vasoconstriction. Our study tried to elucidate the mechanisms
responsible for long-term reduction of blood pressure (BP) in SHR
subjected to early transient captopril treatment. Adult untreated
SHR aged 30-34 weeks were compared with animals subjected to
chronic captopril treatment for 6 weeks either in youth (between
4 and 10 weeks of age) or in adulthood (between 24 and 30
weeks of age). Antihypertensive effects of captopril were more
pronounced in young than adult SHR. This was due to greater
attenuation of sympathetic and nifedipine-sensitive BP
components and prevention of residual BP rise in young
captopril-treated SHR in which the reductions of nifedipinesensitive BP component and residual BP persisted for 20 weeks
after captopril withdrawal. The magnitude of nifedipine-sensitive
component of sympathetic vasoconstriction is decisive for BP
maintenance not only in untreated SHR but also in SHR during
active captopril treatment by or after its withdrawal.