In vitro assessment of diameter-pressure relationship in carotid arteries from normotensive and spontaneously hypertensive rats.
OBJECTIVE
To compare the mechanical properties of carotid arteries from normotensive and spontaneously hypertensive rats.


METHODS
The pressure-diameter relationships of carotid arteries from nine normotensive adult Wistar-Kyoto (WKY) and nine spontaneously hypertensive rats (SHR) were measured in vitro under control conditions and after poisoning the smooth muscle cells with potassium cyanide.


METHODS
Changes in diameter due to changes in transmural pressure were determined with an ultrasonic dimensiometer (12 MHz). The diameter values were determined from the transit times of the pair of echoes given by the proximal and distal walls. The carotid artery was submitted to stepwise increases in pressure of 25 mmHg, from 0 to 200 mmHg; each pressure level was maintained for 5 min before the arterial diameter was recorded.


RESULTS
The carotid artery pressure-diameter relationship was a sigmoid curve in both strains. At the same level of pressure, the diameter of the carotid artery from SHR was significantly larger than that from normotensive rats (P < 0.05). Furthermore, the diameter values measured at the operating mean arterial pressure (roughly 100 mmHg for WKY rats and 150 mmHg for SHR) were markedly different (P < 0.001). In both strains, the diameter under passive conditions (with potassium cyanide) was significantly larger than that measured under control conditions (P < 0.01).


CONCLUSIONS
Carotid arteries from SHR were significantly stiffer than those from WKY rats. Due to the pressure-dependency of the arterial wall stiffness, the increased arterial stiffness reported in hypertensive rats in vivo is related to an increase in distending arterial pressure and also to a significant reduction in the intrinsic compliance of the arterial wall.
Caputo
L
L
INSERM U141, Lariboisière Hospital, Paris, France.
Tedgui
A
A
Poitevin
P
P
Lévy
B I
BI
D000818:Animals; D001794:Blood Pressure / Q000502:physiology*; D002339:Carotid Arteries / Q000033:anatomy & histology / Q000000981:diagnostic imaging / Q000502:physiology*; D003187:Compliance; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D011190:Potassium Cyanide / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR / Q000502:physiology*; D011921:Rats, Inbred WKY / Q000502:physiology*; D014463:Ultrasonography
D011190:Potassium Cyanide