Uptake of triiodothyronine into cultured human muscle cells

Abstract

Abstract. The uptake of T3 was measured in cultured human muscle cells at 37°C and pH 7.4 in a medium containing albumin and glucose. The initial uptake increased linearly when the total T3 concentration was varied from 10−9 to 10−4 m. At prolonged incubation time the uptake decreased to virtually zero in about 30 min. These data indicate a rapid passive transport mechanism of T3 and a fast equilibration of the cellular T3 with the surrounding medium. In agreement with these conclusions the efflux of T3 was rapid and the initial uptake was not altered by pre-incubation in a T3-containing medium.