Effect of Age, Vitamin B6Deficiency, Isoniazid and Deoxypyridoxine on the Urinary Taurine of the Rat

The object of the present study was to find the effects of isoniazid (INH) and deoxypyridoxine (DOP) as well as a vitamin B6deficiency on urinary taurine excretion. Groups of male rats 38 to 47 days of age were fed 5 diets: adequate in vitamin B6, adequate in vitamin B6with INH added, deficient in vitamin B6, and deficient in vitamin B6with INH or DOP added. The urinary taurine of male rats fed adequate vitamin B6remained at about 2 mg/100 g body weight/day up to 50 to 55 days of age, then increased rapidly to about 7 mg at 75 to 95 days of age. The urinary taurine of rats fed diets deficient in vitamin B6remained at 1 to 2 mg over a 7-week period. The urinary taurine of rats fed diets adequate in vitamin B6plus INH and of those fed diets inadequate in vitamin B6plus DOP was significantly higher than that of the controls; the taurine also tended to be higher when rats were fed vitamin B6-deficient diets plus INH. The results are contrary to expectation in view of the known inhibitory effects of the 2 compounds on vitamin B6.