Taurine Pool Sizes in the Rat: Effects of Vitamin B-6 Deficiency and High Taurine Diet

Abstract

The specific activity of taurine was measured in a number of tissues and body fluids of the rat at various times after injection of ³⁵S-taurine. The results provide evidence of separate taurine pools with different characteristics, and estimates of the sizes and half-lives of these pools. The results suggest that a 150 g rat has a rapidly miscible taurine pool of approximately 1.0 mmole with a half-life of 3 days and another, slowly miscible, pool of approximately 1.5 mmoles with a half-life of 24 days. Feeding a vitamin B-6-deficient diet resulted in a markedly decreased excretion of taurine in urine and feces, but not in a decreased total taurine content of the body. The distribution between the pools was changed to approximately 0.5 mmole with no change in half-life and approximately 2.0 mmoles with a manyfold increase in half-life. Supplementing either diet with taurine had little effect on the concentration of taurine in the various tissues, with the exception of liver and plasma, and the extra taurine consumed was recovered almost quantitatively in the urine and feces. Supplementation did have a considerable effect on the kinetics of elimination of the ³⁵S-taurine, especially in animals fed the vitamin B-6-deficient diet, where the half-life of the slowly miscible taurine pool was reduced to the same order of magnitude as that of the control animals. Supplementing the control diet with taurine caused a reduction in the half-life of the rapidly miscible pool.