Physiological roles of taurine in heart and muscle

Abstract

Taurine (aminoethane sulfonic acid) is an ubiquitous compound, found in very high concentrations in heart and muscle. Although taurine is classified as an amino acid, it does not participate in peptide bond formation. Nonetheless, the amino group of taurine is involved in a number of important conjugation reactions as well as in the scavenging of hypochlorous acid. Because taurine is a fairly inert compound, it is an ideal modulator of basic processes, such as osmotic pressure, cation homeostasis, enzyme activity, receptor regulation, cell development and cell signalling. The present review discusses several physiological functions of taurine. First, the observation that taurine depletion leads to the development of a cardiomyopathy indicates a role for taurine in the maintenance of normal contractile function. Evidence is provided that this function of taurine is mediated by changes in the activity of key Ca2+ transporters and the modulation Ca2+ sensitivity of the myofibrils. Second, in some species, taurine is an established osmoregulator, however, in mammalian heart the osmoregulatory function of taurine has recently been questioned. Third, taurine functions as an indirect regulator of oxidative stress. Although this action of taurine has been widely discussed, its mechanism of action is unclear. A potential mechanism for the antioxidant activity of taurine is discussed. Fourth, taurine stabilizes membranes through direct interactions with phospholipids. However, its inhibition of the enzyme, phospholipid N-methyltransferase, alters the phosphatidylcholine and phosphatidylethanolamine content of membranes, which in turn affects the function of key proteins within the membrane. Finally, taurine serves as a modulator of protein kinases and phosphatases within the cardiomyocyte. The mechanism of this action has not been studied. Taurine is a chemically simple compound, but it has profound effects on cells. This has led to the suggestion that taurine is an essential or semi-essential nutrient for many mammals.

Taurine Protects Primary Neonatal Cardiomyocytes Against Apoptosis Induced by Hydrogen Peroxide

“…35) Furthermore, a hypertrophic stimulus, angiotensin II, was also found to promote apoptosis of cardiac myocytes 36) and Tau could reduce the angiotensin II-mediated oxidative stress. 37) Consistently, we found that taurine protected cardiomyocytes against apoptosis induced by H2O2. Taurine enhanced the SOD concentration and inhibited MDA production to a greater extent than did the cells in the H2O2 group.…”

Difference between Plasma Concentrations of Three Amino Acids in Patients with Ischemic and Hemorrhagic Stroke

“…Moreover, taurine deficiency is associated with various pathologies including heart dysfunction [31], abnormalities of brain development [32], and cardiomyopathy [33]. In the astrocytes and the neurons, taurine is the principal osmolyte which during hypotonic or hypertonic conditions it goes out from or accumulates inside the cell, respectively [12].…”

Does a physiological concentration of taurine increase acute muscle power output, time to fatigue, and recovery in isolated mouse soleus (slow) muscle with or without the presence of caffeine?

“…This effect of taurine-caffeine 374 combined was not transferable to skeletal muscle in the present study when used at a physiological 375 level (70µM human maximal) of caffeine concentration and the combined effect was not greater 376 than that of caffeine alone in the present study. Besides the differences in caffeine concentration, 377 10mM caffeine would be highly toxic for human consumption (Fredholm et al 1999), it is considered 378 that the effects of taurine are more profound in heart tissue which may further contribute to the 379 differences in results (Schaffer et al 2010). 380…”