Taurine kinetics assessed using [1,2-¹³C₂]taurine in healthy adult humans

Abstract

Rakotoambinina, Benjamin, Lisa Marks, Abdul Monem Badran, Frank Igliki, François Thuillier, Pascal Crenn, Bernard Messing, and Dominique Darmaun. Taurine kinetics assessed using [1,2-13 C2]taurine in healthy adult humans. Am J Physiol Endocrinol Metab 287: E255-E262, 2004. First published March 9, 2004 10.1152/ajpendo.00333.2003.-To assess the dynamics of taurine metabolism in vivo, two sets of studies were carried out in healthy volunteers. First, pilot studies were carried in a single human subject to determine the time course of plasma and whole blood isotope enrichment over the course of an 8-h, unprimed continuous infusion of [1,2-13 C2]taurine. Second, five healthy adult males received two tracer infusions on separate days and in randomized order: 1) a 6-h continuous infusion of [1,2-13 C2]taurine (3.1 Ϯ 0.2 mol ⅐ kg Ϫ1 ⅐ h Ϫ1 ) and 2) a bolus injection of [13 C2]taurine (3.0 Ϯ 0.1 mol/kg). Isotope enrichments in plasma and whole blood taurine were determined by gas chromatography-mass spectrometry. The pilot experiments allowed us to establish that steady-state isotope enrichment was reached in plasma and whole blood by the 5th h of tracer infusion. The plateau enrichment reached in whole blood was lower than that obtained in plasma taurine (P Ͻ 0.02). In the second set of studies, the appearance rate (Ra) of plasma taurine, determined from continuous infusion studies was 31.8 Ϯ 3.1 mol ⅐ kg Ϫ1 ⅐ h Ϫ1 . After a bolus injection of tracer, the enrichment decay over the subsequent 2 h was best fitted by a two-exponential curve. Taurine Ra was Ϸ85% higher when determined using the bolus injection technique compared with continuous infusion of tracer. We conclude that 1) taurine Ra into plasma is very low in healthy postabsorptive humans, and, due to taurine compartmentation between the extra-and intracellular milieus, may represent only interorgan taurine transfer and merely a small fraction of whole body taurine turnover; and 2) the bolus injection technique may overestimate taurine appearance into plasma. Further studies are warranted to determine whether alterations in bile taurine dynamics affect taurine Ra. constant infusion; bolus injection technique TAURINE (2-ETHANEAMINOSULFONIC ACID) IS, after glutamine, the second most abundant free amino acid in mammalian cells (2) and is involved in various physiological functions, including osmoregulation, defense against oxidative stress, detoxification of xenobiotics, membrane stabilization, retinal function, and bile conjugation (22). The two sources of body taurine are dietary intake and de novo taurine synthesis from methionine and cysteine, its sulfur amino acid precursors (22). Due to the limited taurine synthetic capacity of the newborn, taurine is considered a conditionally essential amino acid in infants (28). Taurine depletion has been described in adult patient populations as well (13, 50), as a result of either 1) increased utilization (11), 2) decreased intake (38), 3) decreased rate of de novo synthesis (45), or 4) various combinations of the thre...

Taurine Intestinal Absorption and Renal Excretion Test in Diabetic Patients

“…The final outcome of taurine homeostasis is through fecal excretion after deconjugation by the bacterial flora or renal excretion as intact molecules (19,(21)(22)(23). In this study at similar half-life in both groups, the urinary excretion rate of taurine was higher in diabetic subjects.…”

Taurine Attenuates Multiple Organ Injury Induced by Intestinal Ischemia Reperfusion in Rats

“…Taurine, present in high concentrations in mammal tissues [9] but depleted during trauma, critical illness, and surgery [10,11], plays a very important role for the majority of homeostatic functions [12]. Taurine protects tissues against attack by down-regulating neutrophil CD11b [13,14] and prevents high glucose-induced endothelial cell apoptosis in vitro [15].…”

Taurine Attenuates Acute Hyperglycaemia-Induced Endothelial Cell Apoptosis, Leucocyte-Endothelial Cell Interactions and Cardiac Dysfunction

“…Intracellular taurine levels are usually very stable with neutrophil, platelet and plasma taurine responsible for the majority of homeostatic functions [25]. Taurine, given intravenously as in this experiment, in the acute setting acts in the intravascular compartment, especially when intracellular taurine is normal [26]. One of its main roles is to protect tissues against attacks by chlorinated oxidants, particularly hypochlorous acid.…”