CHANGES IN PLASMA-LEVELS OF VASOACTIVE SUBSTANCES DURING ROUTINE ACETATE AND BICARBONATE HEMODIALYSIS

Hemodynamic stability is better preserved during bicarbonate hemodialy sis compared to acetate. We have studied the effects of bicarbonate (H DB) and acetate hemodialysis (HDA) on plasma levels of vasoactive subs tances. The treatments were performed for 270 min. A cuprophan plate d ialyzer was used. The ultrafiltration volume and the ultrafiltration r ate were identical in the individual patients during the two treatment s. In the case of vasoconstrictors there was an increase in neuropepti de Y (NPY) (20%, p <0.01) during HDB and arginine vasopressin (AVP) wa s unchanged. Unlike this was the response during HDA when there was no change in NPY and a decrease in AVP (38%, p <0.01). An increase in no radrenaline (NA) (41%, p <0.05) occurred during HDA different from wha t was the case during HDB. There was a gradual increase in renin (PRA) during both HDB (141%, p <0.05) and HDA (148%, p <0.01). With respect to vasodilators there were no differences between the two regimes reg arding calcitonin gene-related peptide (CGRP) and motilin (MOT). The c hange in substance P (SP) during the treatments was also similar but s omewhat more pronounced during HDB. Thus, an initial rise occurred (HD B, 81%, p <0.01; HDA, 36%, p <0.05) followed by a decrease (HDB, 26%, p <0.05) or a tendency to decrease (HDA, 12%, p = 0.058) during the re maining part of the treatment. A rise in beta-endorphin (beta-END) occ urred during HDB (10%, p <0.05) but not during HDA. An increase in vas oactive intestinal peptide (VIP) occurred during HDB (27%, p <0.05) di fferent from the decrease during HDA (11%, p <0.05). Systolic blood pr essure (SBP) and heart rate (HR) remained unchanged during HDB, but du ring HDA a decrease in SBP (154 +/- 11 to 139 +/- 11 mmHg, p <0.05) an d an increase in HR (74 +/- 4 to 77 +/- 3 beats/min, p <0.05) took pla ce. A more pronounced response of vasoconstrictors was observed during HDB compared to HDA. However, the response of vasodilators was also m ore marked with bicarbonate. These data indicate an impaired response of vasoactive substances to the cardiovascular stress of hemodialysis when acetate is used. Thus, bicarbonate hemodialysis seems to be the m ore physiological treatment modality.