Thyroxine 5'-deiodinase in cells isolated from brown adipose tissue of warm- and cold-acclimated guinea pigs.

Abstract

The long-term objective of this study was to prepare isolated brown adipose tissue (BAT) cells which contain either a high or a low level of thyroxine 5$\sp\prime$-deiodinase (T5$\sp\prime$D) activity for future use in the study of the role of this enzyme, which produces the thermogenically active thyroid hormone, 3,5,3$\sp\prime$-triiodothyronine (T$\sb3$), in the regulation of metabolic processes in BAT cells. Cold acclimation was used to increase T5$\sp\prime$D activity in BAT, since it is known to have this effect in rats, hamsters and mice. However, the guinea pig was chosen as experimental animal because this is known to be the only species for which cells isolated from BAT of the cold acclimated animal have a much greater thermogenic response to noradrenaline (NA) than cells from BAT of the warm acclimated animal. T5$\sp\prime$D had not hitherto been studied in BAT of the guinea pig. (Abstract shortened by UMI.)