Cellular characterization of taurine transporter in cultured cardiac myocytes and nonmyocytes.

Abstract

Taurine is by far the most abundant free amino acid in the mammalian heart, comprising in excess of 50% of the total free amino acid pool1,2. Although its physiological function remains undefined, taurine exhibits an extensive cardiovascular pharmacology. Carnivores depend to a large extent on taurine obtained through the diet, which must be transported across cell membranes to accumulate in the heart. The taurine transporter, which belongs to a gene family that encodes Na+-and Cl--coupled transporters2,3has been cloned from mammalian tissues and cells3–10. Although numerous cell types are present in the heart, cardiomyocytes and cardiac fibroblasts are the predominant cell type in the neonatal rat heart. There are no known studies showing the detailed characterization of the taurine transporter in cardiac cells. The present study was undertaken to clarify the physiological characteristics of the cardiac taurine transporter using cultured myocytes and nonmyocytes prepared from neonatal rats.