EFFECT OF RICH UREA PLASMA IN APOPTOSIS OF NEUTROPHILS IN DOGS

Abstract

The acceleration of neutrophil apoptosis in human patients with kidney disease and its relationship with the uremic toxins have been, in recent years, widely investigated due to its importance as an immunosuppressant. Chronic renal failure (CRF) is the most common nephropathy observed in dogs, however, there are no reports in the literature about the effect of uremia in the apoptosis for this species. Considering that urea is the most routinely uremic toxin measured in the CRF clinic addressing, it is proposed to test the hypothesis that urea is able to change the morphology of dog’s neutrophils and to accelerate their programmed cell death and that this effect is dependent on the time of exposure. Blood plasma of ten healthy dogs was replaced by homologue plasma enriched with two different concentrations of urea (114.6 and 62.9 mmol/L) and incubated at 37ºC for four hours. The concentration of urea was determined by UV enzimatic method and the apoptotic index evaluated by morphometry. The rate of apoptotic neutrophils increased after two and four hours of incubation (p<0.05), regardless of the addition of urea. The apoptotic index of neutrophils incubated with plasma rich in urea was higher than those containing non-enriched plasma, but this difference was not significant. In conclusion, the increase of plasmatic urea concentration “ex vivo” alone does not promote the acceleration of dog’s neutrophils apoptosis. It is possible that the “in vivo” immunossupresor effect of urea, is similar to that observed in humans, where it is also associated with other mecanisms and in synergism with others toxins.