Nitric oxide synthetic capacity in relation to dialysate temperature

Background: During hemodialysis, vascular reactivity is impaired, which can be corrected by lowering dialysate temperature. It has also been shown that nitric oxide (NO) is related to intradialytic hypotension. As NO synthesis may be temperature-dependent, this study addressed the influence of dialysate temperature on the NO synthetic capacity of plasma. Methods: NO synthetic capacity was studied during hemodialysis with a dialysate temperature of 37.5degreesC (dialysis-37.5degreesC) and programmed extracorporeal blood cooling (cool dialysis; Blood Temperature Monitor; Fresenius C) in 12 stable patients. NO synthetic capacity was assessed ex vivo by [H-3]L-citrulline formation from [H-3]L-arginine in cultured endothelial cells after incubation with plasma samples obtained during the respective sessions. Results: Core temperature decreased (-0.32 +/- 0.10degreesC) and energy transfer rate was significantly lower (-27.5 +/- 2.8 W; p < 0.05) during cool dialysis compared to dialysis-37.5degreesC (0.19 +/- 0.06degreesC and -0.8 +/- 1.2 W respectively; p < 0.05). Systolic blood pressure decreased during dialysis-37.5degreesC (-19 +/- 4 mm Hg; p < 0.05), but not during cool dialysis (-6 +/- 5 mm Hg). NO synthetic capacity increased during dialysis-37.5degreesC (55.5 +/- 9.3 to 73.5 +/- 10.2 pmol/10(5) cells; p < 0.05), in contrast to cool dialysis (67.3 +/- 11.1 to 66.2 +/- 10.8 pmol/10(5) cells). Conclusion: The stimulatory effect of uremic plasma on endothelial NO synthesis was augmented during dialysis-37.5degreesC but not during cool dialysis. Copyright (C) 2004 S. Karger AG, Basel.