HEPARIN AND VASOACTIVE PEPTIDES IN HEMODIALYSIS-PATIENTS

Plasma concentrations of vasoactive peptides have been reported to be influenced by various procedural features of hemodialysis (HD), such a s ultrafiltration and isovolemic diffusion, dialysate buffer and dialy sate temperature, but also by sham HD thus reflecting an effect of the extracorporeal circulation per se. In the present study the effect of heparin administration was investigated in 9 stable HD patients, and compared with that of saline. Blood samples were taken from the arteri ovenous fistula before and 45 min after the administration of heparin or saline. After an interval of 2 weeks, the procedure was repeated wi th the exception that the patients who received heparin on the first o ccasion were given saline and vice versa. Plasma concentrations of the vasoactive peptides were measured by radioimmunoassay. Regardless of whether heparin was given or not, the plasma concentrations of the vas odilators atrial natriuretic peptide, P-endorphin and vasoactive intes tinal peptide did not change, nor did the concentration of the vasocon strictor neuropeptide Y. The plasma motilin concentration decreased si gnificantly when heparin was given, and that of substance P increased, both these peptides being vasodilators. Mean arterial blood pressure decreased regardless of whether heparin was given or not, and no diffe rence between the two regimens was noted. Heart rate was unchanged wit h both regimens. To sum up, administration of heparin but not of salin e affected the plasma concentrations of motilin and substance P. Howev er, the decrease in blood pressure during the procedure seemed not to be related to the changes in these peptides, as it also occurred in th e absence of heparin.