[Comparison of endothelial reactivity of infrarenal and suprarenal aortic segments in rodents].
OBJECTIVE
Human infrarenal aorta is prone to develop atherosclerotic lesions. Infrarenal aortic blood flow depends on lower limb muscular activity. Blood flow variations cause shear stress variations known to influence endothelial reactivity. The purpose of this study is to compare vascular reactivity of the suprarenal and infrarenal aorta.


METHODS
Endothelium-dependent relaxation to acetylcholine (ACH) and calcium ionophore (Cal), and endothelium-independent relaxation to sodium nitroprussiate (SNP) in 3 aortic segments (thoracic, abdominal suprarenal and infrarenal) harvested from Sprague-Dawley rats (n = 12) were studied in organ chambers.


RESULTS
Endothelium-dependent relaxations to ACH were similar for the 3 aortic segments. However, infrarenal aorta endothelial response to Cal was decreased compared to other segments whereas response to SNP was enhanced. Contractility to vasoconstrictor agonist (phenylephrine and KCl) was diminished compared to the suprarenal segments.


CONCLUSIONS
Endothelial reactivity is not homogeneous throughout the rat aorta. Endothelial reactivity to Cal seems decreased in the infrarenal aorta which suggests a diminished nitric oxide synthase activity. The increased sensitivity of the infrarenal aorta to nitric oxide donor such as SNP suggests a compensatory mechanism.
Elkouri
S
S
Service de Chirurgie, Institut de Cardiologie de Montréal, Québec, Canada.
Demers
P
P
Couturier
A
A
Cartier
R
R
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects*; D001012:Aorta, Abdominal / Q000187:drug effects; D001013:Aorta, Thoracic / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects*; D018056:Hemorheology; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D007668:Kidney; D008297:Male; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D007476:Ionophores; D020030:Nitric Oxide Donors; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine; D011189:Potassium Chloride; D019001:Nitric Oxide Synthase; D000109:Acetylcholine; D002118:Calcium
Comparaison de la réactivité endothéliale des segments aortiques infrarénaux et suprarénaux chez le rongeur.