Determination of hypotaurine and taurine in blood plasma of rats after the administration of L-cysteine.

A method for the simultaneous determination of hypotaurine and taurine was developed. The method consisted of the elimination of urea, which interfered with the determination of hypotaurine, by immobilized urease, and determination of hypotaurine and taurine with an amino acid analyzer. The analyzer equipped with a cation-exchange column was operated at 32 degrees C with 0.2 M sodium citrate buffer, pH 2.8. Using this method, the dynamics of hypotaurine and taurine in blood plasma of rats was studied after the intraperitoneal injection of L-cysteine. The concentration of cysteine reached the maximum 1 h after L-cysteine loading. The concentration of hypotaurine and taurine increased in parallel and reached the maximum 2 h after L-cysteine loading. These changes seem to indicate the precursor-product relationship of these substances and the rapid conversion of hypotaurine to taurine in vivo.