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Maturation is associated with changes in rat cerebral artery structure, biomechanical properties and tone


Correspondence: M. Mandalà, PhD, Department of Obstetrics and Gynecology, University of Vermont College of Medicine, Burlington, VT, USA.




This study evaluated the hypothesis that physiological maturation affects cerebral artery smooth muscle–endothelial interactions involved in pressure-induced tone and alters the dimensional and biomechanical properties of small posterior cerebral arteries (PCA).


Secondary branches of PCA from young (4–5 weeks old, n = 11), adult (14–16 weeks old, n = 11) and mature (44–47 weeks old, n = 11) male Sprague-Dawley rats were isolated, cannulated, pressurized and subjected to a range of intraluminal pressures (10–110 mmHg) to determine tone with and without pharmacologic nitric oxide synthase (NOS) inhibition. Measurements of passive lumen diameter and wall thickness as a function of pressure were used to determine changes in structure, distensibility and wall stress; histological analysis was performed on vessel cross-sections to assess collagen and elastin contents.


Although pressure-dependent tone decreased significantly during ageing, differences between groups were abolished by NOS inhibition. Vessel diameters increased in adult vs. young rats (at 90 mmHg, 233 ± 6.0 μm vs. 192 ± 4.5 μm; P < 0.05), possibly secondary to somatic growth. Further ageing was associated with reductions in lumen diameter (207 ± 6.5 μm; P < 0.05), increased wall and media thickness (and wall/lumen ratio) and cross-sectional area. Distensibility and wall collagen were unchanged, although elastin content was significantly reduced.


Maturation is associated with differences in PCA dimensional properties that indicate a pattern of initial outward eutrophic, followed by inward hypertrophic remodelling. Functionally, the contribution of basal NO increases with age in a way that reduces pressure-dependent tone and diminishes vasodilator reserve.