Taurine’s Modulation of Inotropism in Guinea Pig Heart

Abstract

Since the publication of the pioneer paper of Dolara et al. [1], the biological interactions between taurine and calcium ions have been verified. The effect of taurine on cardiac contraction is clearly calcium-dependent [2,3]. In guinea pig ventricular strips, in the absence of taurine, an increase in the CaCl₂ concentrations in the incubation medium from 0.45 mM to 2.7 mM leads to an increase in the development of the maximum tension (Figure 2–1). The addition of 20 mM taurine to this system produces an additional increase in the maximum tension above the control levels until a CaCl₂ concentration of 1.8 mM is reached [4]. The maximum effect of taurine is measured at 0.9 mM CaCl₂ (Figure 2–1); this effect of taurine is dose-dependent (4–20 mM, Figure 2–2). At a concentration of 2.2 mM CaCl₂ the positive inotropic effect of taurine disappears and at 2.7 mM CaCl₂ becomes negative (Figure 2–1). The positive inotropic effect of taurine is capable of being fully washed out with saline containing 0.9 mM CaCl₂, as demonstrated in Figure 2–3.