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


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Department of Cell Biology, University of Calabria, Arcavacata di Rende, Italy. maurizio.mandala@uvm.edu
M
M
Mandalà
A L
AL
Pedatella
S
S
Morales Palomares
M J
MJ
Cipolla
G
G
Osol
D000375:Aging / Q000473:pathology* / Q000502:physiology*; D000818:Animals; D001696:Biomechanical Phenomena; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002536:Cerebral Arteries / Q000187:drug effects / Q000473:pathology* / Q000502:physiology*; D003094:Collagen / Q000378:metabolism; D004110:Diltiazem / Q000494:pharmacology; D004549:Elastin / Q000378:metabolism; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D023421:Models, Animal; D009131:Muscle, Smooth, Vascular / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000187:drug effects; D010208:Papaverine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*
D004791:Enzyme Inhibitors; D003094:Collagen; D004549:Elastin; D010208:Papaverine; D019001:Nitric Oxide Synthase; D004110:Diltiazem