Polimorfismos de inserção/deleção do gene da ECA e K121Q do gene PC-1 em pacientes com Diabete Mellito tipo 1 normoalbuminúricos : estudo com 10 anos de acompanhamento

O objetivo deste estudo foi analisar o papel do polimorfismo de I/D do gene da Enzima Conversora de Angiotensina (ECA) e o polimorfismo K121Q da PC-1 nas modificações das taxas de filtração glomerular (TFG), excreção urinária de albumina (EUA) e pressão arterial em uma coorte de pacientes diabéticos tipo 1 normoalbuminúricos (EUA<20μg/min) em um estudo com seguimento de 10,2 ± 2,0anos (6,5 a 13,3 anos). A EUA (imunoturbidimetria), TFG (técnica da injeção única de 51Cr-EDTA), HbA1c (cromatografia de troca iônica) e pressão arterial foram medidas no início do estudo e a intervalos de 1,7 ± 0,6 anos. O polimorfismo I/D e K121Q foram determinados através da PCR e restrição enzimática. Onze pacientes apresentaram o genótipo II, 13 o ID e 6 apresentaram o genótipo DD. Pacientes com o alelo D (ID/DD) desenvolveram mais freqüentemente hipertensão arterial e retinopatia diabética. Os 3 pacientes do estudo que desenvolveram nefropatia diabética apresentaram o alelo D. Nos pacientes ID/DD (n=19) ocorreu maior redução da TFG quando comparados com os pacientes II (n=11) (-0,39 ± 0,29 vs – 0,12 ± 0,37 ml/min/mês; P=0,035). A presença do alelo D, em análise de regressão múltipla linear (R2=0,15; F=4,92; P=0,035) foi o único fator associado à redução da TFG (-0,29 ± 0,34 ml/min/mês; P<0,05). Já o aumento da EUA (log EUA = 0,0275 ± 0,042 μg/min/mês; P=0,002) foi associado somente aos níveis iniciais de EUA (R2=0,17; F=5,72; P=0,024). Um aumento significativo (P<0,05) no desenvolvimento de hipertensão arterial e de novos casos de retinopatia diabética foi observado somente nos pacientes com os genótipos ID/DD. Vinte e dois pacientes apresentaram genótipo KK, 7 KQ e 1 apresentou genótipo QQ. Pacientes com os genótipos KQ/QQ apresentaram um aumento significativo (P=0,045) de novos casos de retinopatia diabética. Em conclusão a presença do alelo D nesta amostra de pacientes DM tipo 1 normoalbuminúricos e normotensos está associada com aumento na proporção de complicações microvasculares e hipertensão arterial.

Níveis séricos de endotelina estão aumentados em pacientes com diabetes mellitus tipo 2 e nefropatia diabética

Nefropatia diabética (ND) é uma importante complicação crônica do diabetes mellitus (DM), sendo responsável por uma proporção importante dos novos casos de diálise. Os principais fatores de risco são a hiperglicemia, hipertensão arterial sistêmica (HAS), a dislipidemia e o tabagismo. Está claro que a ND apresenta também um componente genético, entretanto os genes envolvidos na sua etiologia ainda não estão totalmente identificados. O sistema renina-angiotensina (SRA) tem um importante papel na gênese e progressão da ND. Recentemente, acumulam-se evidências que endotelinas também podem participar na patogênese da ND. As endotelinas são peptídeos com potente ação vasoconstritora e atuam modulando o tono vasomotor, proliferação celular e produção hormonal. Estes peptídeos agem através de dois receptores (ET-A e ET-B) que são expressos nas células endoteliais e no músculo liso vascular. Ativação destes receptores nas células renais levam a uma complexa cascata de alterações resultando em proliferação e hipertrofia das células mesangiais, vasoconstrição das arteríolas aferentes e eferentes e acúmulo da matriz extra-celular. Essas alterações hemodinâmicas renais estão associadas com o aparecimento e progressão da doença renal no DM. Níveis plasmáticos elevados de endotelina-1 (ET-1) têm sido relatados em pacientes com DM, tanto com e sem microalbuminúria, sugerindo que a disfunção endotelial relacionada ao DM poderia aumentar a produção vascular de ET-1, que levaria ao dano glomerular. O uso de drogas antagonistas do receptor da ET-1 em situações de DM experimental tem mostrado propriedades nefroprotetoras, reforçando a importância deste sistema na ND.

Curso evolutivo e fatores de progressão da nefropatia diabética em pacientes com diabete melito tipo 2

A nefropatia diabética (ND) é uma complicação microvascular freqüente, que acomete cerca de 40% dos indivíduos com diabete melito (DM). A ND associa-se a significativo aumento de morte por doença cardiovascular. É a principal causa de insuficiência renal terminal em países desenvolvidos e em desenvolvimento, representando, dessa forma, um custo elevado para o sistema de saúde. Os fatores de risco para o desenvolvimento e a progressão da ND mais definidos na literatura são a hiperglicemia e a hipertensão arterial sistêmica. Outros fatores descritos são o fumo, a dislipidemia, o tipo e a quantidade de proteína ingerida na dieta e a presença da retinopatia diabética. Alguns parâmetros de função renal também têm sido estudados como fatores de risco, tais como a excreção urinária de albumina (EUA) normal-alta e a taxa de filtração glomerular excessivamente elevada ou reduzida. Alguns genes candidatos têm sido postulados como risco, mas sem um marcador definitivo. O diagnóstico da ND é estabelecido pela presença de microalbuminúria (nefropatia incipiente: EUA 20-199 μg/min) e macroalbuminúria (nefropatia clínica: EUA ≥ 200 μg/min). À medida que progride a ND, aumenta mais a chance de o paciente morrer de cardiopatia isquêmica. Quando o paciente evolui com perda de função renal, há necessidade de terapia de substituição renal e, em diálise, a mortalidade dos pacientes com DM é muito mais significativa do que nos não-diabéticos, com predomínio das causas cardiovasculares. A progressão nos diferentes estágios da ND não é, no entanto, inexorável. Há estudos de intervenção que demonstram a possibilidade de prevenção e de retardo na evolução da ND principalmente com o uso dos inibidores da enzima conversora da angiotensina, dos bloqueadores da angiotensina II e do tratamento intensivo da hipertensão arterial. Os pacientes podem entrar em remissão, ou até mesmo regredir de estágio. A importância da detecção precoce e da compreensão do curso clínico da ND tem ganhado cada vez mais ênfase, porque a doença renal do DM é a principal causa de diálise no mundo e está associada ao progressivo aumento de morte por causas cardiovasculares.

Renal and antibacterial effects induced by myotoxin I and II isolated from Bothrops jararacussu venom

Bothrops jararacussu myotoxin I (BthTx-I; Lys 49) and II (BthTX-II; Asp 49) were purified by ion-exchange chromatography and reverse phase HPLC. In this work we used the isolated perfused rat kidney method to evaluate the renal effects of B. jararacussu myotoxins I (Lys49 PLA(2)) and II (Asp49 PLA(2)) and their possible blockage by indomethacin. BthTX-1 (5 mu g/ml) and BthTX-II (5 mu g/ml) increased perfusion pressure (PP; ct(120) = 110.28+/-3.70 mmHg; BthTX I = 171.28+/-6.30* mmHg; BthTX II = 175.50+/-7.20* mmHg), renal vascular resistance (RVR; ct(120) = 5.49+/-0.54 mmHg/ml.g(-1) min(-1); BthTX I = 8.62+/-0.37* mmHg/ml g(-1) min(-1); BthTX II=8.9+/-0.36* mmHg/ml g(-1) min(-1)), urinary flow (UF; ct(120)= 0.14+/-0.01 ml g(-1) min(-1); BthTX I=0.32+/-0.05* ml g(-1) min(-1); BthTX II=0.37+/-0.01* ml g(-1) min(-1)) and glomerular filtration rate (GFR; ct(120)=0.72+/-0.10 ml g(-1) min(-1); BthTX I=0.85+/-0.13* ml g(-1) min(-1); BthTX II=1.22+/-0.28* ml g(-1) min(-1)). In contrast decreased the percent of sodium tubular transport (%TNa+; ct(120)=79,76+/-0.56; BthTX I=62.23+/-4.12*; BthTX II=70.96+/-2.93*) and percent of potassium tubular transport (%TK+;ct(120)=66.80+/-3.69; BthTX I=55.76+/-5.57*; BthTX II=50.86+/-6.16*). Indomethacin antagonized the vascular, glomerular and tubular effects promoted by BthTX I and it's partially blocked the effects of BthTX II. In this work also evaluated the antibacterial effects of BthTx-I and BthTx-II against Xanthomonas axonopodis. pv. passiflorae (Gram-negative bacteria) and we observed that both PLA2 showed antibacterial activity. Also we observed that proteins Also we observed that proteins chemically modified with 4-bromophenacyl bromide (rho-BPB) decrease significantly the antibacterial effect of both PLA(2). In conclusion, BthTx I and BthTX II caused renal alteration and presented activity antimicrobial. The indomethacin was able to antagonize totally the renal effects induced by BthTx I and partially the effects promoted by BthTx II, suggesting involvement of inflammatory mediators in the renal effects caused by myotoxins. In the other hand, other effects could be independently of the enzymatic activity of the BthTX II and the C-terminal domain could be involved in both effects promoted for PLA(2). (C) 2005 Elsevier Ltd. All rights reserved.

Renal effects and vascular reactivity induced by Tityus serrulatus venom

Tityus serrulatus, popularly known as yellow scorpion, is one of the most studied scorpion species in South America and its venom has supplied some highly active molecules. The effects of T. serrulatus venom upon the renal physiology in human showed increased renal parameters, urea and creatinine. However, in perfused rat kidney the effects were not tested until now. Isolated kidneys from Wistar rats, weighing 240-280 g, were perfused with Krebs-Henseleit solution containing 6% (g weight) of previously dialysed bovine serum albumin. The effects of T. serrulatus venom were studied on the perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF), glomerular filtration rate (GFR), sodium tubular transport (%TNa+), potassium tubular transport (%TK+) and chloride tubular transport (%TCl-). Tityus serrulatus venom (TsV; 10 mu g/mL) was added to the system 30 min after the beginning of each experiment (n = 6). This 30 min period was used as an internal control. The mesenteric bed was perfused with Krebs solution kept warm at 37 T by a constant flow (4 mL/min), while the variable perfusion pressure was measured by means of a pressure transducer. The direct vascular effects of TsV (10 mu g/mL/min; n=6), infused at a constant rate (0.1 mL/min), were examined and compared to the infusion of the vehicle alone at the same rate. TsV increased PP (PP30'= 127.8 +/- 0.69 vs PP60' = 154.2 +/- 14 mmHg*, *p < 0.05) and RVR (RVR30' = 6.29 +/- 0.25 vs RVR60' = 8.03 +/- 0.82 mmHg/mL g(-1) min(-1)*, *p < 0.05), decreased GFR (GFR(30') =0.58 +/- 0.02 vs GFR(60') = 0.46 +/- 0.01 mL g(-1) min(-1)*, *p < 0.05) and UF (UF30' = 0.135 +/- 0.001 vs UF60' = 0.114 +/- 0.003 mL g(-1)min(-1)*, *p < 0.05). Tubular transport was not affected during the whole experimental period (120 min). on the other hand, the infusion of TsV (10 mu g/mL/min) increased the basal perfusion pressure of isolated arteriolar mesenteric bed (basal pressure: 74.17 +/- 3.42 vs TsV 151.8 +/- 17.82 mmHg*, *p < 0.05). TsV affects renal haemodynamics probably by a direct vasoconstrictor action leading to decreased renal flow. (c) 2005 Elsevier Ltd. All rights reserved.

The role of indomethacin and tezosentan on renal effects induced by Bothrops moojeni Lys49 myotoxin I

Renal changes determined by Lys49 myotoxin I (BmTx I), isolated from Bothrops moojeni are well known. The scope of the present study was to investigate the possible mechanisms involved in the production of these effects by using indomethacin (10 mu g/mL), a non-selective inhibitor of cyclooxygenase, and tezosentan (10 mu g/mL), an endothelin antagonist. By means of the method of mesenteric vascular bed, it has been observed that B. moojeni myotoxin (5 mu g/mL) affects neither basal perfusion pressure nor phenylephrine-preconstricted vessels. This fact suggests that the increase in renal perfusion pressure and in renal vascular resistance did not occur by a direct effect on renal vasculature. Isolated kidneys from Wistar rats, weighing 240-280 g, were perfused with Krebs-Henseleit solution. The infusion of BmTx-I increased perfusion pressure, renal vascular resistance, urinary flow and glomerular filtration rate. Sodium, potassium and chloride tubular transport was reduced after addition of BmTx-I. Indomethacin blocked the effects induced by BmTx-I on perfusion pressure and renal vascular resistance, however, it did not revert the effect on urinary flow and sodium, potassium and chloride tubular transport. The alterations of glomerular filtration rate were inhibited only at 90 min of perfusion. The partial blockade exerted by indomethacin treatment showed that prostaglandins could have been important mediators of BmTx-I renal effects, but the participation of other substances cannot be excluded.The blockage of all renal alterations observed after tezosentan treatment support the hypothesis that endothelin is the major substance involved in the renal pathophysiologic alterations promoted by the Lys49 PLA(2) myotoxin I, isolated from B. moojeni. In conclusion, the rather intense renal effects promoted by B. moojeni myotoxin-I were probably caused by the release of renal endothelin, interfering with the renal parameters studied. (c) 2006 Elsevier Ltd. All rights reserved.

Purification and renal effects of phospholipase A(2) isolated from Bothrops insularis venom

Bothrops insularis venom contains a variety of substances presumably responsible for several pharmacological effects. We investigated the biochemical and biological effects of phospholipase A(2) protein isolated from B. insularis venom and the chromatographic profile showed 7 main fractions and the main phospholipase A(2) (PLA(2)) enzymatic activity was detected in fractions IV and V. Fraction IV was submitted to a new chromatographic procedure on ion exchange chromatography, which allowed the elution of 5 main fractions designated as lV-1 to IV-5, from which lV-4 constituted the main fraction. The molecular homogeneity of this fraction was characterized by high-performance liquid chromatography (HPLC) and demonstrated by mass spectrometry (MS), which showed a molecular mass of 13984.20 Da; its N-terminal sequence presented a high amino acid identity (up to 95%) with the PLA(2) of Bothrops jararaca and Bothrops asper. Phospholipase A(2) isolated from B. insularis (Bi PLA(2)) venom (10 mu g/mL) was also studied as to its effect on the renal function of isolated perfused kidneys of Wistar rats (n = 6). Bi PLA(2) increased perfusion pressure (PP), renal vascular resistance (RVR), urinary flow (UF) and glomerular filtration rate (GFR). Sodium (%TNa+) and chloride tubular reabsorption (%TCl-) decreased at 120 min, without alteration in potassium transport. In conclusion, PLA(2) isolated from B. insularis venom promoted renal alterations in the isolated perfused rat kidney. (c) 2007 Elsevier Ltd. All rights reserved.

Purification and characterization of the biological effects of phospholipase A(2) from sea anemone Bunodosoma caissarum

Sea anemones contain a variety of biologically active substances. Bunodosoma caissarum is a sea anemone from the Cnidaria phylum, found only in Brazilian coastal waters. The aim of the present work was to study the biological effects of PLA(2) isolated from the sea anemone B. caissarum on the isolated perfused kidney, the arteriolar mesenteric bed and on insulin secretion. Specimens of B. caissarum were collected from the Sao Vicente Channel on the southern coast of the State of São Paulo, Brazil. Reverse phase HPLC analysis of the crude extract of B. caissarum detected three PLA(2) proteins (named BcPLA(2)1, BCPLA(2)2 and BcPLA(2)3) found to be active in B. caissarum extracts. MALDI-TOF mass spectrometry of BcPLA(2)1 showed one main peak at 14.7 kDa. The N-terminal amino acid sequence of BcPLA(2)1 showed high amino acid sequence identity with PLA(2) group III protein isolated from the Mexican lizard (PA23 HELSU, HELSU, PA22 HELSU) and with the honey bee Apis mellifera (PLA(2) and 1POC_A). In addition, BcPLA(2)1 also showed significant overall homology to bee PLA(2). The enzymatic activity induced by native BCPLA(2)1 (20 mu g/well) was reduced by chemical treatment with p-bromophenacyl bromide (p-BPB) and with morin. BcPLA(2)1 strongly induced insulin secretion in presence of high glucose concentration. In isolated kidney, the PLA(2) from B. caissarum increased the perfusion pressure, renal vascular resistance, urinary flow, glomerular filtration rate, and sodium, potassium and chloride levels of excretion. BcPLA(2)1, however, did not increase the perfusion pressure on the mesenteric vascular bed. In conclusion, PLA(2), a group III phospholipase isolated from the sea anemone B. caissarum, exerted effects on renal function and induced insulin secretion in conditions of high glucose concentration. (C) 2009 Elsevier Ltd. All rights reserved.

Purification and biological effects of a C-type lectin isolated from Bothrops moojeni

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Renal and vascular effects of the natriuretic peptide isolated from Crotalus durissus cascavella venom

Crotalus durissus cascavella is a snake that is usually found in the scrublands of northeast Brazil. The components of its venom may have effects on the vascular and renal systems. Recently, a new bradykinin inhibitory peptide has been identified in the venom of the Crotalinae family. The aim of the present study was to investigate the renal and vascular effects of the natriuretic peptide isolated from the venom of Crotalus durissus cascavella (NP2_Casca). The chromatographic profile showed the fractionation of substances identified as convulxin, gyroxin, crotoxin and crotamine, as well as fractions V and VI. The electrophoretic profile of fraction V consisted of several bands ranging from approximately 6 kDa to 13 kDa, while fraction VI showed only two main electrophoretic bands with molecular weights of approximately 6 and 14 kDa. Reverse-phase chromatography showed that NP2_Casca corresponds to about 18% of fraction VI and that this fraction is the main natriuretic peptide. NP2_Casca was compared to other natriuretic peptides from other sources of snake venom. All amino acid sequences that were compared showed a consensus region of XGCFGX, XLDRIX and XSGLGCX. The group treated with NP2-Casca showed an increase in perfusion pressure, renal vascular resistance, urinary flow and glomerular filtration rate. The percent of total and proximal tubular transport of sodium was reduced significantly after administration of the peptide. The mean arterial pressure showed a dose-dependent decrease after infusion of NP2_Casca, and an increase in nitrite production. In the aortic ring assay, NP2_Casca caused a relaxant effect in endothelium-intact thoracic aortic rings precontracted with phenylephrine in the presence and absence of isatin. NP2_Casca failed to relax the aortic rings precontracted with an isosmotic potassium Krebs-Henseleit solution. In conclusion, the natriuretic peptide isolated from Crotalus durissus cascavella venom produced renal and vascular effects. NP2_Casca reduced total and proximal sodium tubular transport, leading to an increase in sodium excretion, thereby demonstrating a diuretic action. A hypotensive effect was displayed in an arterial pressure assay, with an increase in nitrite production, suggesting a possible vasoactive action. (C) 2008 Elsevier Ltd. All rights reserved.

Renal- and calcium-dependent vascular effects of Polybia paulista wasp venom

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Renal and cardiovascular effects of Bothrops marajoensis venom and phospholipase A(2)

Bothrops marajoensis is found in the savannah of Marajo Island in the State of Par S and regions of Amapa State, Brazil. The aim of the work was to study the renal and cardiovascular effects of the B. marajoensis venom and phospholipase A(2) (PLA(2)). The venom was fractionated by Protein Pack 5PW. N-terminal amino acid sequencing of sPLA(2) showed amino acid identity with other lysine K49sPLA(2)s of snake venom. B. marajoensis venom (30 mu g/mL) decreased the perfusion pressure, renal vascular resistance, urinary flow, glomerular filtration rate and sodium tubular transport. PLA(2) did not change the renal parameters. The perfusion pressure of the mesenteric bed did not change after infusion of venom. In isolated heart, the venom decreased the force of contraction and increased PP but did not change coronary flow. In the arterial pressure, the venom and PLA(2) decreased mean arterial pressure and cardiac frequency. The presence of atrial flutter and late hyperpolarisation reversed, indicating QRS complex arrhythmia and dysfunction in atrial conduction. In conclusion, B. marajoensis venom and PLA(2) induce hypotension and bradycardia while simultaneously blocking electrical conduction in the heart. Moreover, the decrease in glomerular filtration rate, urinary flow and electrolyte transport demonstrates physiological changes to the renal system. (C) 2009 Elsevier Ltd. All rights reserved.

Histopatologia de fígado, rim e baço de piaractus mesopotamicus, prochilodus lineatus e pseudoplatystoma fasciatum parasitados por myxosporídios, capturados no Rio Aquidauana, Mato Grosso do Sul, Brasil

Este estudo descreveu a histopatologia de rim, baço e fígado de Piaractus mesopotamicus, Prochilodus lineatus e Pseudoplatystoma fasciatum, parasitados por mixosporídios, capturados no Rio Aquidauana, MS. Após necropsia, amostras do fígado, rim cefálico e baço foram colhidas, fixadas em formalina a 10 % tamponada e processadas de acordo com a rotina histológica. Os cortes foram feitos à espessura de 5 μm e corados com hematoxilina-eosina. Foram encontrados Myxobolus porofilus em P. lineatus, M. colossomatis em P. mesopotamicus e Myxobolus spp. nas três espécies de hospedeiros. Cistos de mixosporídios no exame histopatológico foram vistos no fígado e baço de P. mesopotamicus. Mais de 50% das amostras de fígado de P mesopotamicus e P lineatus apresentou hepatodistrofia difusa. Mais de 80 % das amostras de fígado de P. fasciatum apresentou formações hialinas concêntricas e esteatose em 50% das amostras. em 95,23 % das amostras de rins de P. mesopotamicus, foram observadas alterações teciduais, e em mais de 60 % dos casos nefrodistrofia difusa moderada e congestão de sinusóides glomerulares. Alterações teciduais nas amostras de rins de P. lineatus foram observadas em menos de 20 % da amostra. No baço dos peixes ora examinados não foram encontradas lesões dignas de relato.

Avaliação da presença de osteopatia decorremte do diabetes tipo 1 em criança e adolecentes do Rio Grande do Norte

Diabetes Mellitus (DM) and osteoposes are chronic diseases with great socioeconomic consequences, mainly due to the late complications and consequent disabilities. The potential effects of DM on bone metabolism remain a very conroversial issue, and disagreement exists with regard to the clinical implications of diabetic osteopenia and the mechanism of its ocurrence. The issue is further complicated by the contribuicion of the especific factors, such as duration of disease an dthe degree of metabolic control. The objective of this study is to identify the osteopathy in children and adolescents with DM 1 assisted in the hospital of pediatrics, UFRN, through biochemical markers of bone and mineral metabolism and the extent of bone mineral density. The study was composed by 74 diabetics type 1 patients (DM1) of both gender and aged 6 to 20 yars. Normoglicêmic group was composed by 97 healthy subjects of both genders, which showed the same age range of DM1, in addition to same socioeconomic class. These individuals qere students from the networks of public education in the city of Natal-RN, randomly invited to paticipate in our study. Both groups DM1 and NG were divided intofour subgroups, according to the classification of tanner , T1, T2, T3, T4 for achieving a benchmark. Diabetic individuals showed up with a poor glycemic control. the group DN1 T4 showed an incresead value for total protein, albumin, urea and microalbumiuria are predictors of grumelura injury in DM1 patients . The total alkaline phosphatase activitywas kept on high levels for both groups because they are in a stature development age. For osteocalcin there were decreased levels for groups Dm1 T1, T2, and T3 when compared to their NG (s), suggesting that this decrease could be associated with reduction in the number and/or differentiation os osteoblasts thereby contributing to reducing bone formation. There were no changes in the activity of TRAP. The serum concentrations of total and ionized calcium, phosphorus and magnesium were included within the RV. It was observed that the BMD (Z- SCORE ) has always been within the RV for both groups, despite to DM1 T4. Taking all together, our results support the hypothesis that children and adolescents with type 1 DM present the risk in the long run to suffer a reduction in the bone mass, associated to poor glicemic control and disease duration. It could limit the bone growth and increase the probality of development of osteopenia, as well as other complications surch as retinopathy and renal failure

Participação da excreção renal de cálcio, fósforo, sódio e potássio na homeostase em cães sadios e cães com doença renal crônica

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.