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BACKGROUND/AIMS: Despite the increasing evidence for the role of nitric oxide (NO) in hemodialysis hypotension, the source of NO is still debated. Heparin stimulates NO production by the cultured human endothelial cells in vitro. The aim of this study is to compare the effects of unfractionated heparin and parnaparin, low molecular weight heparin, on the NO production and arterial pressure of hemodialysis patients during hypotensive episodes.
METHODS: Ten hemodialysis patients with hypotensive periods on maintenance hemodialysis therapy were involved in this study. Serum NO were obtained at the beginning of dialysis, during hypotensive episode and at the end of dialysis in the last hemodialysis session after 3 weeks of use of heparin and parnaparin for anticoagulation.
RESULTS: NO levels were 39.4±13.2 M at the beginning of hemodialysis, 92.4±31.4 M during hypotensive episode (p<0.05) and 43.1±25.1 M at the end of dialysis with heparin. In parnaparin period, NO levels were 47.2±22.7 M at the beginning, 80.7±46.5 M at the hypotensive episode (p<0.05) and 45.8^23.2 M at the end of session. Percent increase in NO levels during hypotensive period compared to the beginning of haemodialysis with heparin were significantly higher than parnaparin (140.2±50.4 % vs. 119.6±44.8 %, p<0,05). Percent decrease in mean arterial pressure with heparin was significantly higher than parnaparin (48.6±6.4 % vs. 39.6± 5.3 %, p<0,05).
CONCLUSION: Decrease in mean arterial pressure and increase in NO production during hypotensive episodes were less prominent with parnaparin use compared to heparin and this difference might be related to their endothelial binding capacity, thrombin affinity and/or effects on platelet functions.