Efeitos da relação amido: proteína, da hidroxiprolina e do sódio na produção de urina e excreção renal de oxalato e cálcio em gatos
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Data
2019-11-12
Autores
Mendonça, Fernanda Sanches [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O presente estudo avaliou diferentes ingestões de amido, proteína, hidroxiprolina e sódio sobre o balanço hídrico, formação e excreção de oxalato, excreção renal de cálcio e a SSR OxCa e estruvita em gatos. Para isto, foram formuladas 8 dietas experimentais: 1 - baixa proteína (alto amido), hidroxiprolina e Na; 2 - baixa proteína (alto amido), alta hidroxiprolina e baixo Na; 3 - baixa proteína (alto amido), baixa hidroxiprolina e alto Na; 4 - baixa proteína (alto amido), alta hidroxiprolina e Na; 5 - alta proteína (baixo amido) e hidroxiprolina e baixo Na; 6 - alta proteína (baixo amido), baixa hidroxiprolina e baixo Na; 7 - alta proteína (baixo amido), baixa hidroxiprolina e alto Na; 8 - alta proteína (baixo amido), hidroxiprolina e Na. O experimento foi realizado em DIC, em esquema fatorial 2x2x2 (dois níveis, alto e baixo, de relação proteína:amido, de sódio e de hidroxiprolina), totalizando 8 dietas, 56 gatos, 7 gatos por dieta. Os gatos receberam os alimentos experimentais por 21 dias, sendo adaptados às dietas por 10 dias, seguidos de 8 dias de coleta total de fezes e urina. No dia 19 e 20 foi realizada hemogasometria, com coleta de sangue em jejum (19 dia) e 8h após expostos aos alimentos (20 dia). No dia 1 e 21, foi mensurada PAS pelo método Doppler. Na urina foi aferido o pH, volume, densidade, macrominerais, oxalato, citrato, ácido úrico e amônia. Com base nestes resultados foram calculadas as SSR OxCa e estruvita. Os dados foram submetidos à análise de variância, médias comparadas pelo teste de Tukey e contrastes de interesse (P<0,05). A PAS não diferiu entre as dietas experimentais e tempos basal vs final, confirmando que a curto prazo dietas de alto Na não causam hipertensão nos gatos. O pH urinário foi mais alcalino nas dietas com maior teor de proteína, evidenciando que esta, por si só, não é responsável pela acidificação do pH da urina. O consumo de alta proteína e Na aumentaram excreção de água e alteraram a densidade da urina de modo oposto, no qual, dietas de alta proteína aumentaram a densidade devido sua carga osmótica e as de alto sódio reduziram pela maior excreção de água livre, contudo, o maior volume urinário não foi compensado pelo aumento da ingestão hídrica (P>0,05). O consumo das dietas de alto Na aumentou a excreção renal de Ca em 25% e reduziu a excreção renal de citrato, ambos fatores podem contribuir para formação de urólitos de OxCa. Gatos consumindo alto amido e hidroxiprolina apresentaram aumento na concentração urinária e excreção renal de oxalato e SSR OxCa, evidenciando a problemática no consumo desses nutrientes quando se trata de urolítiase por oxalato de cálcio. Com isso, conclui-se que as dietas com proteína e Na elevados promovem diurese em gatos. O consumo de alimentos com elevado amido e hidroxiprolina induziu aumento da formação de oxalato endógeno, verificado pelo aumento da excreção renal e da concentração urinária de oxalato pelos gatos, fatores que resultaram em maior SSR OxCa. O consumo de dietas com Na elevado aumentou a excreção renal de Ca e reduziu a de citrato, assim, mesmo tendo induzido diurese não reduziu a SSR OxCa. Por outro lado, essa elevação do Na do alimento reduziu a SSR para estruvita, em função da diurese com redução do teor de P da urina.
The present study evaluated different intakes of starch, protein, hydroxyproline and sodium on water balance, oxalate formation and excretion, renal calcium excretion and RSS OxCa and struvite in cats. For this, 8 experimental diets were formulated: 1 - low protein (high starch), hydroxyproline and Na; 2 - low protein (high starch), high hydroxyproline and low Na; 3 - low protein (high starch), low hydroxyproline and high Na; 4 - low protein (high starch), high hydroxyproline and Na; 5 - high protein (low starch) and hydroxyproline and low Na; 6 - high protein (low starch), low hydroxyproline and low Na; 7 - high protein (low starch), low hydroxyproline and high Na; 8 - high protein (low starch), hydroxyproline and Na. The experiment was carried out in CRD, with a 2x2x2 factorial scheme (two levels, high and low, protein: starch ratio, Na and hydroxyproline), totaling 8 diets, 56 cats, 7 cats per diet. Cats received experimental feed for 21 days, were adapted to the diets for 10 days, followed by 8 days of total fecal and urine collection. On day 19 and 20, blood gas analysis was performed, blood was collected fasting (19 day) and 8h after exposure to food (20 day). On days 1 and 21, SBP was measured by the Doppler method. In urine, were measured pH, volume, density, macrominerals, oxalate, citrate, uric acid and ammonia. Based on these results RSS CaOx and struvite were calculated. Data were subjected to analysis of variance, means compared by Tukey test and contrasts of interest (P <0.05). SBP did not differ between experimental diets and baseline vs final times, confirming that in short term Na does not increase blood pressure in cats. Urinary pH was more alkaline in diets with higher protein content, evidencing that this alone is not responsible for acidifying urine pH. Consumption of high protein and Na increased water excretion and altered urine density in the opposite way, which high protein increased density due to its osmotic load and high Na reduced by higher free water excretion, however, the increased on urinary volume was not compensated by increased water intake (P>0,05). Consumption of high Na diets increased renal Ca excretion by 25% and reduced renal excretion of citrate, both factors may contribute to the formation of calcium oxalate uroliths. Cats consuming high starch and hydroxyproline showed increased urinary concentration and renal excretion of oxalate and RSS OxCa, highlighting the problem in the consumption of these nutrients when it comes to calcium oxalate urolithiasis. Thus, it was concluded that high protein and Na diets promote diuresis in cats. Consumption of high starch and hydroxyproline foods induced an increase in endogenous oxalate formation, verified by the increase of renal excretion and urinary oxalate concentration in cats, factors that resulted in higher RSS OxCa. Consumption of high Na diets increased renal Ca excretion and reduced citrate excretion, so even though induced diuresis did not reduce RSS OxCa. On the other hand, this increase in food Na reduced the RSS for struvite, due to diuresis with reduced in urine P content.
The present study evaluated different intakes of starch, protein, hydroxyproline and sodium on water balance, oxalate formation and excretion, renal calcium excretion and RSS OxCa and struvite in cats. For this, 8 experimental diets were formulated: 1 - low protein (high starch), hydroxyproline and Na; 2 - low protein (high starch), high hydroxyproline and low Na; 3 - low protein (high starch), low hydroxyproline and high Na; 4 - low protein (high starch), high hydroxyproline and Na; 5 - high protein (low starch) and hydroxyproline and low Na; 6 - high protein (low starch), low hydroxyproline and low Na; 7 - high protein (low starch), low hydroxyproline and high Na; 8 - high protein (low starch), hydroxyproline and Na. The experiment was carried out in CRD, with a 2x2x2 factorial scheme (two levels, high and low, protein: starch ratio, Na and hydroxyproline), totaling 8 diets, 56 cats, 7 cats per diet. Cats received experimental feed for 21 days, were adapted to the diets for 10 days, followed by 8 days of total fecal and urine collection. On day 19 and 20, blood gas analysis was performed, blood was collected fasting (19 day) and 8h after exposure to food (20 day). On days 1 and 21, SBP was measured by the Doppler method. In urine, were measured pH, volume, density, macrominerals, oxalate, citrate, uric acid and ammonia. Based on these results RSS CaOx and struvite were calculated. Data were subjected to analysis of variance, means compared by Tukey test and contrasts of interest (P <0.05). SBP did not differ between experimental diets and baseline vs final times, confirming that in short term Na does not increase blood pressure in cats. Urinary pH was more alkaline in diets with higher protein content, evidencing that this alone is not responsible for acidifying urine pH. Consumption of high protein and Na increased water excretion and altered urine density in the opposite way, which high protein increased density due to its osmotic load and high Na reduced by higher free water excretion, however, the increased on urinary volume was not compensated by increased water intake (P>0,05). Consumption of high Na diets increased renal Ca excretion by 25% and reduced renal excretion of citrate, both factors may contribute to the formation of calcium oxalate uroliths. Cats consuming high starch and hydroxyproline showed increased urinary concentration and renal excretion of oxalate and RSS OxCa, highlighting the problem in the consumption of these nutrients when it comes to calcium oxalate urolithiasis. Thus, it was concluded that high protein and Na diets promote diuresis in cats. Consumption of high starch and hydroxyproline foods induced an increase in endogenous oxalate formation, verified by the increase of renal excretion and urinary oxalate concentration in cats, factors that resulted in higher RSS OxCa. Consumption of high Na diets increased renal Ca excretion and reduced citrate excretion, so even though induced diuresis did not reduce RSS OxCa. On the other hand, this increase in food Na reduced the RSS for struvite, due to diuresis with reduced in urine P content.
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Palavras-chave
Aparelho urinário Cálculos, Gatos, Rações, Sódio, Proteínas