Alterations in flow-dependent vasomotor tone in spontaneously hypertensive rats.
We studied the effect of endothelium on the flow-induced response of conductance arteries and the resistance arteriolar network in an in situ model of perfused mesenteric artery in normotensive Wistar-Kyoto and spontaneously hypertensive rats. The mesenteric network was perfused with a Tyrode's albumin solution. The diameter of a conductance mesenteric artery was measured using a video camera system, and mesenteric pressure was recorded in a collateral artery. The preparation was perfused at 0.2, 2, and 4 mL/min, and flow-diameter-pressure relations were established (1) under control conditions, (2) during local inhibition of nitric oxide synthesis by topical application of N omega-nitro-L-arginine methyl ester (L-NAME) (1 mmol/L), and (3) after endothelium removal (CO2 drying). In normotensive rats, L-NAME decreased conductance artery diameter by 12 +/- 2% (P < .01) at 0.2 mL/min and 3.3 +/- 1.9% (P < .05) at 2 mL/min. In hypertensive rats, L-NAME did not modify mesenteric diameter. Endothelium removal markedly increased arterial resistance in both strains and decreased conductance artery diameter in normotensive rats (10.3 +/- 3%, P < .05 at 0.2 mL/min and 4.2 +/- 2%, P < .05 at 2 mL/min) but not in hypertensive rats. The present study suggests that the endothelium plays a similar role in the control of mesenteric resistance in both strains and that there is a significant diameter-flow dependency affected by both endothelium removal and inhibition of nitric oxide synthesis in conductance mesenteric arteries from normotensive but not from hypertensive rats.
Qiu
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Institut National de la Santé et de la Recherche Médicale, Unit 141, Université Paris VII, Hôpital Lariboisière, France.
Henrion
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D
Levy
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D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D004730:Endothelium, Vascular / Q000502:physiology*; D006973:Hypertension / Q000503:physiopathology*; D008638:Mesenteric Arteries / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors* / Q000378:metabolism; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D012039:Regional Blood Flow / Q000187:drug effects; D013045:Species Specificity; D014655:Vascular Resistance / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*
D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester