Morphological and functional alterations of mesenteric small resistance arteries in early renal hypertension in rats.
We investigated the structure and reactivity of small resistance arteries of two-kidney, one-clip (2K,1C) and one-kidney, one-clip (1K,1C) Goldblatt hypertensive rats within 4-6 wk of development of hypertension. Blood vessels from the mesenteric vascular bed with lumen diameter less than 300 microns were mounted on a wire myograph. The media of the vessel wall was significantly increased and lumen diameter was decreased in 2K,1C and 1K,1C rats. External diameter of blood vessels was reduced in both 2K,1C and 1K,1C rats, whereas cross-sectional area of the wall was increased significantly in 1K,1C rats. Wall tension in response to KCl was significantly lower in 2K,1C and 1K,1C hypertensive rats, whereas tension in response to norepinephrine (NE) was reduced in 1K,1C hypertensive rats but was similar in 2K,1C rats and controls. Active tension in response to arginine vasopressin (AVP) was similar in all groups. As a consequence of the reduced lumen circumference of small arteries, effective pressure in response to NE was similar in hypertensive and control rats, whereas effective pressure in response to AVP was exaggerated in the hypertensive rats. The sensitivity to NE and AVP was similar in all groups. These results show the rapid development of functional and structural changes in small resistance arteries in renal hypertensive rats within 4-6 wk of hypertension, with significant reduction in external and lumen diameters, increased media width, and increased media-to-lumen ratio, which enhance vascular reactivity to vasoconstrictors, in particular NE and AVP.
Clinical Research Institute of Montreal, Quebec, Canada.
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Deng
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Schiffrin
D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology; D006978:Hypertension, Renovascular / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D008638:Mesenteric Arteries / Q000473:pathology / Q000503:physiopathology*; D009638:Norepinephrine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D013997:Time Factors; D014655:Vascular Resistance; D014661:Vasoconstriction / Q000187:drug effects
D001127:Arginine Vasopressin; D011189:Potassium Chloride; D009638:Norepinephrine