Differential alterations of common carotid and femoral artery distensibility in 12-week-old spontaneously hypertensive rats.
OBJECTIVE
In essential hypertension, the mechanical properties of the radial artery have been shown to be largely unaltered, whereas more controversial and less reliable data have been obtained for the common carotid artery. We therefore examined the distensibility/pressure relationships of the predominantly elastic common carotid artery and of the predominantly muscle-type femoral artery in 12-week-old normotensive Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR).


METHODS
Eleven 12-week-old SHR and 10 age-matched WKY rats were anesthetized with sodium pentobarbitone. Blood pressure and pulse rate were measured by catheters inserted in the common carotid and in the femoral arteries, while contralateral arterial diameter was continuously recorded via an echo-tracking device. Arterial compliance was derived according to the Langewouters formula, and its values were normalized for the diameter, to obtain distensibility/pressure curves and to calculate the distensibility index. The Peterson elastic modulus was also calculated in order to obtain a pressure-independent estimate of arterial mechanical properties.


RESULTS
Femoral artery distensibility/pressure curves and distensibility index were similar in the two groups of rats, the latter being 1.13+/-0.13 mm/mmHg10(-3) in SHR and 1.28+/-0.15 mm/mmHg10(-3) in WKY rats (means+/-SEM; NS). In contrast, in SHR, common carotid artery mechanical properties were clearly impaired, as shown by a marked reduction in distensibility index (2.55+/-0.16 mm/mmHg10(-3) in SHR versus 3.4+/-0.3 mm/mmHg10(-3) in WKY rats; P< 0.05), and by a significant increase in the Peterson elastic modulus.


CONCLUSIONS
In the SHR model, high blood pressure alters the mechanics of large arteries even in the relatively early stage of the disease; however, the alterations are not homogeneous inasmuch elastic-type vessels are affected to a much greater extent than muscle-type vessels.
Stella
M L
ML
CNR and Ospedale Maggiore di Milano, Italy.
Mircoli
L
L
Mangoni
A A
AA
Giannattasio
C
C
Ferrari
A U
AU
Mancia
G
G
D000818:Animals; D001794:Blood Pressure; D017536:Carotid Artery, Common / Q000000981:diagnostic imaging / Q000503:physiopathology*; D004195:Disease Models, Animal; D004548:Elasticity; D005263:Femoral Artery / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006973:Hypertension / Q000000981:diagnostic imaging / Q000503:physiopathology*; D009131:Muscle, Smooth, Vascular / Q000503:physiopathology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D014463:Ultrasonography; D014661:Vasoconstriction