P1052ASUPPRESSION OF BLOOD COAGULATION ON THE SURFACE OF A DIALYSIS MEMBRANE USING A DIALYSATE CONTAINING 800 PPM OF NITRIC OXIDE

Abstract

Abstract Background and Aims Activation of platelets and leukocytes when blood comes in contact with a dialysis membrane surface leads to increased oxidative stress and release of proinflammatory cytokines, which may result in complications in dialysis patients. Within the blood vessels, nitric oxide (NO) generated by nitric oxide synthase on the endothelial cells suppresses both aggregation/activation of platelets and migration/adhesion of leukocytes. We previously showed in a rat hemodialysis model that NO (800 ppm) gas added to the dialysate can suppress blood coagulation on the surface of a dialysis membrane. The aim of the present study was to determine, using a rat hemodialysis model, the appropriate concentration of NO that would most effectively prevent blood coagulation without causing any adverse effects. Method Male Sprague Dawley rats weighing 300 to 400 g were used for the experiments. After the rats were anesthetized (isoflurane, 1.5%-3.0%), extracorporeal circulation was established by removal of blood from the carotid artery and returning it to the tail vein. During the experiment, the blood flow rate was kept at 1.0 mL/min, and the dialysate flow rate at 3 mL/min. Heparin was administered by bolus injection (0.7 unit/g-mouse) at the start of the hemodialysis, and no further heparin was added during the 4-hour hemodialysis session. A cellulose triacetate membrane and polymethylpentene membrane were used for making the small dialyzer and gas exchanger, respectively (the prototype module was manufactured by NIPRO, Co., Japan). NO (200 ppm, 400 ppm, or 800 ppm) was added to the dialysate via the gas exchanger in the NO groups, and N2 gas was added to the dialysate in the control group. During the experiment, the arterial pressure, dialyzer inlet pressure, venous pressure, activated whole blood clotting time (ACT) and methemoglobin (met-Hb) concentration were measured. After circulation, the amount of coagulated blood was measured by the hemoglobin (Hb) content and lactate dehydrogenase (LDH) activity in the eluate from the residual blood clotting in the dialyzer. Results The 4-hour hemodialysis session achievement rate was highest in the NO-800 ppm group (control, 54%; NO-200 ppm, 66%; NO-400 ppm, 77%; NO-800 ppm, 85%). The blood met-Hb content was below 10% in all the NO groups. The Hb content and LDH activity in the eluate were significantly lower in the NO groups than in the control group. These results indicate that addition of higher concentrations of NO was associated with a lower likelihood of coagulation on the dialyzer and in the dialysis circuit and a higher likelihood of smooth and successful 4-hour dialysis sessions. Addition of NO was associated with little risk of adverse effects such as met-Hb accumulation and reduction of blood pressure. Therefore, 800 ppm is considered as the most appropriate concentration of NO to be added to the dialysate for effectively inhibiting blood coagulation without causing any adverse effects. Conclusion Our experiment in a rat hemodialysis model showed that 800 ppm was the most appropriate concentration of NO to be added to the dialysate to suppress blood coagulation on the surface of the dialysis membrane without causing any adverse effects.