Affiliations: Department of Food and Nutrition, Yonsei University,
Seoul 120-749, South Korea
Note: [] Address for correspondence: Dr. Taesun Park, Department of Food
and Nutrition, Yonsei University, 134 Shinchon-dong, Sudaemun-ku, Seoul
120-749, South Korea. Tel.: +82 2 2123 3123; Fax: +82 2 312 5229; E-mail:
tspark@yonsei.ac.kr
Abstract: This study was undertaken to evaluate effects of exercise-induced
hormones, cortisol, IGF-1, and β-endorphin, on the regulation of taurine
transport activity in rat skeletal myoblasts, L6 cells. Challenge of L6 cells
with cortisol (100 nM) for 24 hrs resulted in a 165% increase in taurine
transport activity, 220% increase in V_{max} of the taurine
transporter, and 55% increase in taurine transporter/ β-actin mRNA level
compared with untreated control cells. Neither IGF-1 (1∼100 nM) nor
β-endorphin (1∼20 nM), added in the incubation medium separately for
24 hrs, affected taurine uptake by L6 cells. However, when cells were
co-treated with IGF-1 (10 nM) plus cortisol (100~nM), taurine transport
activity (37% increase, p < 0.05), V_{max} of the
transporter (54%, p < 0.05), and taurine transporter/ β-actin mRNA level
were further increased compared to the value for cells treated with cortisol
alone. These results suggest that taurine transport by skeletal muscle cells
appear to be synergistically up-regulated during a prolonged exercise via
elevated levels of cortisol and IGF-1 in muscle.
