Efflux of T4 from the in situ perfused liver of rainbow trout: effect of T4, dithiothreitol and cysteine in the perfusate.
A Cortland saline-perfused rainbow trout (Oncorhynchus mykiss) liver model was used to study aspects of T4 efflux from the intact organ system. There was a consistent efflux of T4 in the absence of T4 in the perfusate, and the T4 efflux was increased in the presence of T4 in the perfusate, but the efflux was not T4-dose dependent. The addition of the thiol-containing compound dithiothreitol (DTT, 2 mM) to the perfusate had no significant effect on the flux of T4 from the liver, whereas the addition of cysteine (2 mM), a thiol-containing amino acid suppressed T4 efflux. The results are consistent with the known mechanisms of thyroid hormone trafficking across cell membranes, and suggest that organ systems, such as the liver, may act as a major reserve of hormone, thus participating in plasma thyroid hormone homeostasis.
Brett
S E
SE
Department of Biomedical Sciences, University of Guelph, Ont., Canada.
Leary
S C
SC
Welsh
D G
DG
Leatherland
J F
JF
D000818:Animals; D003545:Cysteine / Q000494:pharmacology*; D004229:Dithiothreitol / Q000494:pharmacology*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000502:physiology*; D017686:Oncorhynchus mykiss; D010477:Perfusion; D013974:Thyroxine / Q000378:metabolism* / Q000494:pharmacology*
D003545:Cysteine; D013974:Thyroxine; D004229:Dithiothreitol