The contribution of medial calcification to vascular dysfunction in renal failure is unknown. Vascular function was measured ex vivo in control, noncalcified uremic, and calcified uremic aortas from rats with adenine-induced renal failure. Plasma urea was 16 + 4, 93 + 14, and 110 + 25 mg/dl, and aortic calcium was 27 + 4, 29 + 2, and 4946 + 1616 nmol/mg dry weight respectively in the three groups. Maximal contraction by phenylephrine (PE) or KCl was reduced 53 % and 63 % in uremic aortas and sensitivity, EC50 value, to KCl but not PE was increased. Maximal relaxation to acetylcholine was impaired in uremic aortas (30 % vs. 65 %) and sensitivity to nitroprusside was also reduced, indicating some impairment of endothelium-independent relaxation as well. None of these parameters differed between calcified and noncalcified uremic aortas. However, aortic compliance was reduced in calcified aortas, ranging from 17 % to 61 % depending on the severity of calcification. We conclude that uremic vascular calcification, even when not severe, significantly reduces arterial compliance. Vascular smooth muscle and endothelial function are altered in renal failure but are not affected by medial calcification, even when severe.
- cardiovascular disease
- renal failure
- vascular smooth muscle
- Copyright © 2010, American Journal of Physiology - Renal Physiology