Modulation of Ca2+ and Na+ Transport by Taurine in Heart and Vascular Smooth Muscle

Acute effects of taurine on intracellular calcium in normal and diabetic cardiac myocytes

“…The lesser effect of taurine on control cells at the higher stimulus frequencies is consistent with an enantiostatic action of taurine as has been proposed by Huxtable [16]. This enantiostatic effect was suggested by several different studies in which taurine was found to exert effects on contraction and ion movements to produce changes in different directions depending upon the prevailing conditions of the cell [5,10,26]. In general, under conditions where [Ca 2+ ] is low, taurine acts to increase contractility, whilst if contractility is already high, taurine tends to decrease it or produce little change.…”

“…The increase in the amplitude of the Ca 2+ transient suggests that taurine may be increasing the flux of Ca 2+ into the cell. Enhancement of both the L-type Ca 2+ current and the fast component of the inward Na + current by taurine has been reported [5,26]. A taurine-mediated increase in the Ltype Ca 2+ current would increase Ca 2+ entry directly, while an increase in Na + current could have indirect effects via increased intracellular Na + levels and subsequent entry of Ca 2+ via the Na + /Ca 2+ exchanger.…”

“…For example, taurine has been shown to affect L-type Ca 2+ channels [5,6,29], Ca 2+ transport by the sarcoplasmic reticulum (SR) [28,29,31], K + and Na + currents [5,26] and the Na + /Ca 2+ exchanger [29,31]. The mechanisms by which taurine modulates the activity of these ion-handling pathways are not known, but may involve changes in membrane phospholipid microenvironments [15] or second messenger-mediated effects through binding to specific receptors [7].…”

MAPK activation and apoptotic alterations in hearts subjected to calcium paradox are attenuated by taurine

“…Treatment with different concentrations of taurine (2, 10 or 30 mM) was performed by incubating the fura-2 AM-loaded cells in a buffer containing taurine for 60 min at room temperature before the addition of KCl (30 mM), a known depolarizing agent or ATP (50 μM), a known purinergic receptor agonist [14,17]. It is pointed out that both KCl and ATP are known to cause increase in [Ca 2+ ] i in isolated cardiomyocytes [14,17] whereas the selection of different concentrations of taurine was based on the previous observations [18]. Treatments with different pharmacological agents, which are known to modulate [Ca 2+ ] i , were performed by incubating the fura-2 loaded cells in the buffer containing the desired concentration of pharmacological agents for 10 min before the measurement of fluorescence.…”

Effects of taurine on the reactivity of aortas from diabetic rats

“…Therefore, subsequent experiments on these tissues were carried out using 10 mM taurine. This higher concentration of the nutrient was also used by other investigators in a number of different in vitro experiments (Li et al, 1996;Franconi et al, 1982;Bkaily et al, 1996;Nandhini and Anuradha, 2003). For determination of the involvement of PKC in NE-and PDB-induced contraction, responses to the drugs were obtained in aortas pretreated with calphostin C (3 μM) for 20 min Mueed et al, 2005).…”