Key Points
- To assess how age, contractile stimuli, and the vascular endothelium influence nifedipine-induced relaxation in aortic tissue from normotensive and spontaneously hypertensive rats.
- Examined isolated aortic rings from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) across four age cohorts: 5 weeks, 3 months, 6 months, and 1.5 years.
- Precontracted aortic segments using 50 mM potassium or 0.1 µM noradrenaline, evaluating relaxation responses to nifedipine with and without an intact endothelium.
- In potassium-precontracted vessels, nifedipine relaxation declined at 1.5 years in WKY rats but peaked at 1.5 years in SHR, with SHR exhibiting consistently greater relaxation than age-matched WKY rats.
- Under noradrenaline precontraction, relaxation increased at 6 months and 1.5 years relative to younger ages across strains, occurring independently of endothelial removal.
- Endothelial presence modulated potassium-induced responses divergence-wise, enhancing relaxation in SHR segments while dampening relaxation in WKY segments across ages.
Structured PICO
PPopulationAortic segments from Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) aged 5 weeks, 3 months, 6 months, and 1.5 years
CComparatorComparison across different ages, strains (WKY vs SHR), and endothelium status (intact vs removed)
OOutcomeAortic segment relaxation after precontraction with 50 mM K+ or 0.1 microM noradrenaline (NA)surrogate
In a rat model, the vasorelaxant effect of nifedipine is influenced by age, strain (hypertensive vs normotensive), and endothelial function.