These results suggest that, in women, DeltaP(aug) is highly heritable, is associated with the ratio of distal to proximal arterial diameters, and, independent of PWV, is a major determinant of cPP.

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1 Low density lipoprotein (LDL) inhibits endothelium-dependent relaxation. The mechanism is uncertain, but increased production of superoxide anion O 2 7 with inactivation of endothelium-derived NO and formation of toxic free radical species have been implicated. We investigated e ects of the cell permeable superoxide dismutase mimetic manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin (MnTMPyP), the free radical scavenger vitamin C and arginine (which may reduce O 2 7 formation) on acute LDL-induced endothelial dysfunction in rabbit aortic rings, using LDL prepared by ultracentrifugation of plasma from healthy men and aortic rings from New Zealand white rabbits. 2 LDL (150 mg protein ml 71 for 20 min) markedly inhibited relaxation of aortic rings (in Krebs' solution at 378C and pre-constricted to 80% maximum tension with noradrenaline) to acetylcholine 82+10% (mean percentage di erence between sum of relaxations after each concentration of acetylcholine in the presence and absence of LDL, +s.e.mean, n=26, P50.001) but not to the endothelium-independent agonist nitroprusside. 3 MnTMPyP (10 mM) reduced inhibitory e ects of LDL from 124+27 to 56+17% (n=6, P50.05). 4 Vitamin C (1 mM) reduced inhibitory e ects of LDL from 59+8 to 22+5% (n=6, P50.05).5 Inhibitory e ects of LDL were similar in the absence or presence of arginine (84+12 vs 79+16%, n=14, P=0.55). E ects of L-arginine (10 mM) did not di er signi®cantly from those of D-arginine (10 mM). 6 Acute (20 min) exposure of aortic rings to LDL impairs endothelium-dependent relaxation which can be partially restored by MnTMPyP and vitamin C. This is consistent with LDL causing increased O 2 7 generation.

Background:Pulse wave velocity (PWV), a measure of arterial stiffness strongly predictive of cardiovascular risk in adults, is usually measured by sequential ECG-referenced carotid and femoral tonometry. A simplified technique, more suitable for use in children, employs simultaneous volumetric recording from a sensor applied over the carotid artery and a cuff applied over the femoral artery or arm and thigh pressure cuffs applied over the brachial and femoral arteries. The purpose of this study was to compare PWV computed over the carotid-femoral path (PWVcf) with that over the brachial-femoral path (PWVbf) using a volumetric system (Vicorder) and to compare values of PWVcf obtained by the volumetric and a tonometric method (SphygmoCor) in children.Method:Vicorder PWVcf and PWVbf were compared in 156 children (3–18 years, 110 with chronic kidney disease), and PWVcf by Vicorder was compared to PWVcf by SphygmoCor in a subset of 122 patients.Results:PWVcf by Vicorder was moderately correlated with PWVcf by SphygmoCor (R = 0.50, P < 0.000). PWVbf and PWVcf Vicorder were more closely correlated (R = 0.75, P < 0.0001), but with a significant systematic difference. Applying a correction factor to PWVbf measurements gave results similar to those obtained over the carotid-femoral path. Within-patient coefficients of variation for repeated measures were 5.9, 7.8, and 8.5% for PWVbf (Vicorder), PWVcf (Vicorder) and PWVcf (SphygmoCor), respectively. All PWV values showed a similar relation to age.Conclusion:Volumetric methods appear reproducible and are easy to use in children, but values obtained by Vicorder and SphygmoCor are not interchangeable even when measured over the same pathway.