Increased nitric oxide plasma concentration in dogs with naturally acquired chronic renal disease

ABSTRACT: This study aimed to determine the amount of plasma nitric oxide in clinically stable dogs at different stages of chronic kidney disease (CKD). Five groups of dogs were studied, aged from 4 to 18, comprising of a control group composed of healthy animals (control n=17), group CKD stage 1 (DRC-1, n=12), group CKD stage 2 (CKD-2, n=10) group, CKD stages 3 (CRD-3, n=13) and Group CKD stage 4 (DRC-4, n=10). Dogs with CKD were clinically stable and received no treatment. Two blood samples were collected at 24 hours intervals (repeated measures) to obtain serum and plasma. The serum creatinine values were used to classify dogs as CG, CKD-1, CKD-2, CKD-3 and CKD-4, and were (1.02±0.02mg/dL), (1.07±0.04mg/dL), (1.81±0.03mg/dL), (3.40±0.15mg/dL) and (6.00±0.20mg/dL) respectively. The determination of nitric oxide (NO) was performed by dosing nitrate/nitrite indirectly, and used for measurement of nitrate according to the NO/ozone chemiluminescence. The data were submitted to ANOVA for nonparametric analysis(Kruskal-Wallis) (P<0.05). The concentration of plasmatic NO did not differ significantly among GC (10.81±0.51μM), CKD-1 (15.49±1.97μM) and CKD-2 (19.83±3.31μM) groups. The plasma concentration of CKD-3 (17.02±1.73μM) and CKD-4 (83.56±13.63μM) was significantly higher compared with healthy dogs. In conclusion, the NO plasma concentration can increase in dogs with CKD and become significantly higher in stage 3 and 4 dogs

Participação da excreção renal de cálcio, fósforo, sódio e potássio na homeostase em cães sadios e cães com doença renal crônica Participation of renal excretion of calcium, phosphorus, sodium and potassium on the homeostasis in healthy dogs and in dogs with chronic kidney disease

Na doença renal crônica (DRC) a manutenção da homeostase de água e sódio é o primeiro problema a ser contornado pelo organismo e com o agravamento das lesões renais surgem outros problemas graves relacionados à homeostase de cálcio e fósforo. O presente estudo tem por escopo avaliar a excreção renal de cálcio, fósforo, sódio e potássio, e o perfil sérico destes eletrólitos em cães normais e em cães com DRC naturalmente adquirida. Foram avaliados três grupos de cães adultos, machos ou fêmeas, de raças variadas. Animais normais compuseram o grupo controle (G1) e os cães com DRC foram distribuídos em dois grupos de acordo com os estágios de comprometimento da função renal (G2 e G3, respectivamente, estágios 1-2 e estágios 3-4, descritos pela IRIS 2006 staging CKD). Os cães do G3 apresentaram aumento das concentrações séricas de cálcio ionizado e fósforo, além de diminuição da concentração sérica de sódio. Quanto à excreção renal dos eletrólitos analisados, os animais dos grupos G1 e G2 apresentaram diminuição de carga filtrada e aumento de excreção fracionada, mas as excreções urinárias não variaram significativamente. Os resultados são indicativos de que os rins de cães com DRC podem manter a excreção urinária dos eletrólitos em valores se melhantes aos dos normais. O mecanismo envolve aumento da excreção fracionada na medida em que haja diminuição da filtração glomerular. Esse processo de compensação, entretanto, pode perder a eficiência nos estágios mais avançados da enfermidade no que se refere à manutenção das concentrações séricas de fósforo e sódio.<br>In chronic kidney disease (CKD), the first problem to be solved by the organism is to maintain water and sodium homeostasis and, with the worsening of the renal injuries, other severe problems related to the calcium and phosphorus homeostasis emerge. The present study has the purpose to evaluate the renal excretion and serum profile of calcium, phosphorus, sodium and potassium in healthy dogs and in dogs with naturally acquired CKD. Three groups of adult male and female dogs of varied breeds were evaluated. Normal dogs were in the control group (G1) and the CKD dogs were distributed into two groups in accordance with the stage of renal function impairment (G2 e G3, respectively, stages 1-2 and stages 3-4, proposed by IRIS 2006 staging CKD). The G3 dogs showed increased serum levels of ionized calcium and phosphorus, in addition to the reduction of sodium levels. Regarding the renal excretion of the analyzed electrolytes, the G1 and G2 groups showed a decrease of filtered load and increase of fractional excretion, yet there were no significant variations on the urinary excretions. The results suggest that the kidneys of the CKD dogs can maintain similar values of electrolytes urinary excretion as the kidneys of normal dogs. The mechanism involves an increase of fractional excretion while glomerular filtration decreases. This compensation process, however, can lose its efficiency in the later stages of the disease, in relation to the maintenance of phosphorus and sodium serum levels