DELAYED DECREASE IN PLASMA-LEVELS OF ATRIAL-NATRIURETIC-PEPTIDE DURING COLD HEMODIALYSIS

The high plasma levels of the vasodilating hormone atrial natriuretic peptide (alpha-ANP), observed in patients with chronic renal failure, decrease substantially during hemodialysis (HD), probably owing to vol ume reduction. Cardiovascular stability is better maintained by the us e of cold dialysate although underlying mechanisms are unknown. In ord er to investigate the effects of different dialysate temperatures on h emodynamic stability and plasma levels of immunoreactive ANP (p-irANP) , 10 stable HD patients were dialyzed with bicarbonate dialysis fluid for 240 min with each of 3 different dialysate temperatures: 36.5 degr ees C (normal HD; NHD), 38.5 degrees C (warm HD; WHD) and 34.5 degrees C (cold HD; CHD). A Cuprophan plate dialyzer was used. The ultrafiltr ation volume and ultrafiltration rate were identical in each patient d uring the treatments. p-irANP was determined by radioimmunoassay, usin g 2 antisera which different cross-reactivity to ANP-related peptides. During NHD a nonsignificant decrease in mean arterial blood pressure from 111+/-5 to 103+/-8 mm Hg was observed. A significant (p<0.05) dec rease in mean arterial blood pressure from 109+/-4 to 96+/-6 mm Hg occ urred during WHD, while during CHD it remained stable (111+/-4 before, 112+/-5mm Hg after). Irrespective of the dialysate temperature or the antiserum used, p-irANP decreased significantly (p<0.05) during the t reatment. The reduction in p-irANP was delayed during CHD, the decreas e being significantly (p<0.05) less pronounced after 120 min. At the e nd of the treatment no significant difference was observed between the regimes. In conclusion, together with the improvement of hemodynamic stability during CHD a delayed decrease in p-irANP was observed. Thus, alpha-ANP does not seem to be primarily involved in the stabilization of blood pressure during cold HD.