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KMID : 0811719970010050537
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Korean Journal of Physiology & Pharmacology
1997 Volume.1 No. 5 p.537 ~ p.546
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Role of Intracellular Taurine in Monensin-induced Na＋, Ca2＋ Accumulation and Mechanical Dysfunction in Isolated Rat Hearts
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Young-hoon Kim
Jong-wan Park/Myung-suk Kim
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Abstract
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It has been postulated that the intracellular taurine is co-transported with Na+down a concentration gradient and prevents the intracellular accumulation of sodium. It is therefore, expected that an elevated level of intracellular taurine prevents the sodium-promoted calcium influx to protect the cellular damages associated with sodium and calcium overload. In the present study, we evaluated the effects of intra- and extracellular taurine on the myocardial Na+andCa++ contents and the cardiac functions in isolated rat hearts which were loaded with sodium by monensin, a Na+?ionophore. Monensin caused a dose-dependent increase in intracellular Na+ accompanied with a subsequent increase in intracellular Ca++ and a mechanical dysfunction. In this monensin-treated heart, myocardial taurine content was decreased with a concomittent increase in the release of taurine. The monensin-induced increases in intracellular Na+, Ca++ and depression of cardiac function were prevented in the hearts of which taurine content had been increased by high-taurine diet. Conversely, in the hearts of which taurine concentration gradient had been decreased by addition of taurine in the perfusate, the monensin-induced increases in Na+, Ca++ and functional depression were accelerated. These results suggest that taurine, depending on the intra-extracellular concentration gradient, can affect intracellular sodium and calcium concentrations, and that an increased intracellular taurine may play a role in protection of myocardial dysfunction associated with the sodium and calcium overload.
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KEYWORD
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Taurine, Monensin, Na＋, Ca2＋, Cardiac function,
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