Taurine antagonizes the increase in intracellular calcium concentration induced by α-adrenergic stimulation in freshly isolated guinea-pig cardiomyocytes

• Published in: Journal of molecular and cellular cardiology Vol. 24; no. 11; pp. 1253 - 1265
• Main Authors: Failli, Paola, Fazzini, Alessandro, Franconi, Flavia, Stendardi, Isabella, Giotti, Alberto
• Format: Journal Article
• Language: English
• Published: Kent Elsevier Ltd 01.11.1992; Elsevier
• Subjects: Adult cardiomyocytes; Animals; Biological and medical sciences; Calcium - metabolism; Fundamental and applied biological sciences. Psychology; Fura-2; Guinea Pigs; Heart; Heart - drug effects; In Vitro Techniques; Intracellular calcium concentration; Intracellular Fluid - drug effects; Intracellular Fluid - metabolism; Male; Myocardium - cytology; Myocardium - metabolism; Phenylephrine - pharmacology; Taurine; Taurine - pharmacology; Vertebrates: cardiovascular system; α-adrenoceptor stimulation; β-alanine; Taurine; β-alanine; Adult cardiomyocytes; Intracellular calcium concentration; α-adrenoceptor stimulation; Heart; Calcium; Rodentia; Stimulation; Myocyte; Vertebrata; Mammalia; Guinea pig; α-Adrenergic receptor; Concentration effect; Circulatory system; Antagonist; Intracellular
• ISSN: 0022-2828; 1095-8584
• DOI: 10.1016/0022-2828(92)93092-X

The effect of taurine on phenylephrine α-adrenergic action was studied in freshly-isolated guinea-pig ventricular myocytes. Intracellular calcium concentration was measured at nearly physiological extracellular CaCl 2 in both cell suspension using quin-2 (mean intracellular calcium concentration 154.0±8.0 n m, n=24), and single myocyte with fura-2 (mean intracellular calcium concentration 159.0±20.0 n m, n=23). Phenylephrine increased intracellular calcium concentration in both preparations. In cell suspensions in the presence of 10 −6 m propranolol and at 2.2 m m extracellular calcium concentration, phenylephrine dose-dependently (3 × 10 −7–10 −5 m) increased intracellular calcium concentration, its effect being abolished in the presence of phentolamine. Taurine 20 m m in the incubation fluid increased taurine content in the cells from 110±7 nmol/mg to 317±49 nmol/mg of total proteins. In the range 0.5–20 m m, taurine concentration-dependently reduced the phenylephrine-induced intracellular calcium increase in cell suspensions and 20 m m taurine decreased the effect of 10 −5 m phenylephrine (measured in the presence of 10 −6 m propranolol) by about 80%. β-Alanine (20 m m) did not modify the phenylephrine effect. Our data show that the “protective” effect of taurine in in vitro cardiac preparations and in cardiomyocyte isolation procedures is due to its effect on cardiomyocyte intracellular calcium ion concentration, and that taurine specifically antagonizes α-adrenoceptor activation.