Abstract 588: Attenuation of Flow- and Nitrate-mediated Vasodilation in End-stage Renal Disease by Inflammation, Hyperphosphatemia and Hyperparathyroidism: Correction with Fall in C-reactive Protein by Nocturnal Hemodialysis
Background: Endothelium-dependent vasodilation (EDV) and endothelium-independent vasodilation (EIV) are impaired in end-stage renal disease (ESRD), yet improve soon after conversion from conventional (CHD) to nocturnal hemodialysis (NHD).
Methods and Results: To test the hypotheses that suppression of inflammation and correction of hyperphosphatemia contribute to such improvement, dialysis dose, blood pressure (BP), brachial artery EDV and EIV, plasma C reactive protein (CRP), phosphate (Pi) and parathyroid hormone (PTH) were determined before, 1 and 2 months after conversion to NHD (n=23; mean age: 43±2 years [mean±SEM]). NHD increased dialysis dose, EDV and EIV (all p<0.05) and lowered simultaneously measured BP, Pi and PTH (all p<0.05) and CRP (from 14.8±3.9 to 6.63±2.1 mg/L after 2 months, p<0.01). Overall, there was a significant inverse relationship between EDV and log10CRP (r=−0.35, p=0.008). Pre-specified dichotomization by CHD Pi identified higher BP with Pi <1.8mM (n=10): (147±10/87±7 vs. 131±4/75±2 mmHg, p<0.01), yet after 1 month both groups were normotensive. In those with Pi <1.8mM, 1 month of NHD lowered CRP and increased EDV from −2.4±2.4 to 7.5±1.8% (p<0.05). In contrast, in the high Pi group, NHD lowered Pi (p<0.05) but had no significant effect on CRP, PTH or EDV (−0.8±1.1 vs. −0.6±1.6 %) but after 2 months, Pi and PTH fell and EDV and EIV improved.
Conclusions: Correction of uremia and hypertension alone does not improve endothelial and smooth muscle brachial artery dilation in ESRD; contributions of systemic inflammation, altered Pi balance and hyperparathyroidism to impaired EDV and EIV must also be addressed. We provide the first demonstration that NHD reduces CRP.