Changes in urinary and plasma taurine and amino acids have been evaluated in trained runners competing in the Rotterdam Marathon, 1998, both immediately after completing the event and 24h after recovery. There were significant changes in the urinary amino acids excretion, the majority showing a significant decrease both immediately at the completion of the Marathon and after 24h recovery. In contrast urinary taurine excretion increased immediately post Marathon, although not significantly as the range of results was wide. Such changes in urinary taurine correlated with percentage changes in plasma creatine kinase both immediately post race, (r = 0.972, P < 0.001), and 24h later (r = 0.872, P < 0.001), possibly indicating that the source of the taurine was muscle. Significant correlations between the individual values for urinary and plasma amino acids in all of the athletes were calculated for taurine (r = 0.528), glycine (r = 0.853), threonine (r = 0.749), alanine (r = 0.747), serine (r = 0.620), glutamine (0.614), arginine (r = 0.507), histidine (r = 0.470) and valine (r = 0.486). Changes in the mean plasma concentrations of amino acids were comparable to our previously published data (Ward et al., 1999) the majority showing significant decreases immediately and 24h post Marathon, such an adaptation being due primarily to their utilisation for gluconeogenesis. However, in contrast, the mean taurine concentrations were significantly elevated both post race, P < 0.01 and after 24h, P < 0.05. The physiological response by the muscle to exhaustive exercise, particularly with regard to changes in plasma and urinary taurine concentrations remain to be elucidated, but is probably related to muscle function impairment. The increase in taurine urinary excretion could be used as an indicator of muscle damage occurring during exhaustive exercise. Whether taurine supplementation would minimise such changes is an interesting scientific question and merits investigation.

The sulphonated amino acid taurine increased significantly in the plasma of trained athletes after three endurance exercises of different duration and intensity, a 90 min run on a treadmill at 75% of an individual's VO2 peak, a Marathon, 42.2 km and a 100 km run, by 19%, 77% and 36%, respectively. Such results indicated that the speed at which the exercise is performed, referred to as the intensity, rather than the duration of the exercise, correlated with the elevated taurine levels possibly indicating its release from muscle fibres. The plasma amino acid pool decreased significantly in relationship with the duration of the exercise, caused by their utilisation for glucogenesis. The possible sources of the increased plasma taurine are discussed.

Taurine is released by contracting muscles, but its actual role remains unspecified. In this study, we investigated whether the exercise-stimulated release of taurine from muscle into the plasma regulates the modification of osmolality induced by intramuscular osmolyte production. Six subjects performed 90 min of cycling exercise (at 70% maximum power output) on two occasions, with (HC) or without (DC) fluid intake. Taurine content was determined in plasma, blood cells and urine before and after the endurance events, together with plasma osmolality. Plasma osmolality increased by 4% in the DC experiment ( P<0.01), but remained stable in the HC condition. The exercise also induced changes in the mean (SD) plasma taurine content to a greater degree in HC [+63 (26)%] than in DC [+33 (18)%; P<0.05], supporting the hypothesis that taurine is released into the plasma via an osmoregulatory process. However, the higher plasma taurine content in HC was not related to changes in renal taurine. In addition, the increase of taurine in plasma was not related to its release from blood cells since their taurine concentration increased by 70% both in HC [429 (77) to 680 (82) microM; P=0.003] and in DC [451 (57) to 731 (34) microM; P<0.001]. The lack of correlation between plasma volume modification and the mass ratio of taurine would exclude a major role for taurine exchange in plasma volume regulation. Sodium ( R=0.967, P<0.001), chloride ( R=0.917, P<0.001) and osmolality ( R=0.924, P<0.001) seem to be the main regulators of plasma volume changes during exercise. In conclusion, changes in the plasma taurine content during endurance exercise is related to an osmoregulatory process, but this alone does not control plasma volume changes.

Suzuki cross-coupling reactions of 3-pyrroleboronic acid derivatives with haloaromatics and the reverse process i.e., the coupling of 3-iodo(bromo)pyrroles with arylboronic acids have been investigated as a potential key step in the synthesis of (-)-rhazinilam and analogues. It was found that 3-iodo-2-formyl-1-tosylpyrroles efficiently coupled with a variety of arylboronic acids in the presence of PdCl 2 (dppf) as catalyst. This catalytic system is compatible with a broad spectrum of arylboronic acids -electron-rich, electron-poor, hindered, heterocyclic -which easily coupled with the pyrrole substrate.Résumé : Nous avons étudié les réactions de couplage de Suzuki entre les acides 3-pyrroleboroniques et divers aromatiques halogénés ainsi que les réactions inverses de couplage entre les 3-iodo(bromo)-pyrroles avec des acides boroniques aromatiques. Cette réaction de couplage pourrait être une étape clé dans la synthèse du (-)-rhazinilame. Nous avons découvert que les 3-bromo-et 3-iodo-2-formyl-1-tosylpyrroles pouvaient être couplés efficacement avec un grand nombre d'acides boroniques en utilisant PdCl 2 (dppf) comme catalyseur. Ce catalyseur permet d'introduire facilement une grande diversité d'acides arylboroniques (riches ou pauvres en électrons, encombrés ou hétérocycliques) en position 3 du pyrrole.

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