EFFECT OF TAURINE ON ANGIOTENSIN-II-INDUCED HYPERTROPHY OF NEONATAL RAT CARDIAC-CELLS

The effect of taurine on angiotensin II-induced hypertrophy of culture d neonatal rat heart cells (myocytes and nonmyocytes) was examined. An giotensin II (1-100 nM) alone caused an increase in the rate of protei n synthesis of myocytes without changing the rate of DNA synthesis and cell number. It mediated increases in DNA synthesis and cell number i n nonmyocytes. Furthermore, at the lower concentration of 1 nM, it ind uced c-Sos and c-jun expression in both cultured myocytes and nonmyocy tes. Exposure of the cells to taurine (20 mM) in the absence of angiot ensin II had no effect on either hyperplastic growth or immediate earl y response gene expression by the two types of cultured cardiac cells. However, myocytes pretreated for 24 h with 20 mM taurine exhibited re duced responsiveness to angiotensin II(I nM), resulting in lower level s of angiotensin II-mediated stimulation in protein synthesis, and imm ediate early response gene expression was attenuated. Similarly, tauri ne treatment of nonmyocytes reduced the degree of hyperplastic growth (DNA synthesis and cell number) and immediate early response gene expr ession stimulated by angiotensin II. Finally, taurine partially preven ted the increase in intracellular free calcium [Ca2+](i) mediated by a ngiotensin II in cardiac cells. Our results indicate that taurine is a n effective inhibitor of angiotensin II action.