Taurine metabolism in experimental renal failure.

Taurine is important for the regulation of ionic fluxes in excitable tissues, especially in heart where it is the most abundant amino acid. To investigate a possible role of taurine in uremia, we measured the taurine concentrations in plasma, liver, muscle, heart, and brain tissues of young male Wistar rats. Two groups of rats were studied: (1) rats with acute renal failure (ARF) 12, 24, and 48 hours after bilateral nephrectomy and (2) rats with chronic renal failure (CRF) studied 3 weeks after 5/6 nephrectomy. In ARF animals, taurine increased in plasma and liver two to three times the normal levels, remained unchanged in muscle and brain, but decreased in heart tissue; this decrease (-20%) was significantly correlated with the concomitant increase of BUN and plasma creatinine. In CRF animals, taurine was unchanged in plasma, liver, muscle, and heart, but was increased by 70% in brain accompanied by a high content of gamma-aminoisobutyric acid. The data suggest that in uremia accumulation of taurine is counteracted by increased hepatic elimination and/or decreased synthesis. The depletion of taurine in cardiac muscle might be related to the development of uremic heart disease. The increased concentrations of brain taurine might represent a compensation for the increased neuroexcitability in CRF.