Differential effect of triiodothyronine and thyroxine on liposomes containing cholesterol: physiological speculations

The effect of thyroid hormones on the steady-state fluorescence polarization and on the release of the liposomal content was analyzed in liposomes composed of egg phosphatidylcholine and egg phosphatidyl choline:cholesterol in different molar ratios. Depending on liposome cholesterol composition, a...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of membrane biology 1995-09, Vol.147 (2), p.217-221
Main Authors: Chehin, R N, Rintoul, M R, Morero, R D, Farias, R N
Format: Article
Language:English
Subjects:
Cholesterol - chemistry
Fluorescence Polarization
Hydrogen-Ion Concentration
In Vitro Techniques
Liposomes
Phosphatidylcholines - chemistry
Thyroxine - pharmacology
Thyroxine - physiology
Triiodothyronine - pharmacology
Triiodothyronine - physiology
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The effect of thyroid hormones on the steady-state fluorescence polarization and on the release of the liposomal content was analyzed in liposomes composed of egg phosphatidylcholine and egg phosphatidyl choline:cholesterol in different molar ratios. Depending on liposome cholesterol composition, a dual effect of triiodothyronine was found. The fluorescence polarization of 1,6 diphenyl 1,3,5 hexatriene or 1-(4-trimethylaminophenyl) 6 phenyl-1, 3, 5 hexatriene decreased by the addition of the hormone when cholesterol content was in the range from 0 to 30 moles %, while it increased with cholesterol from 30 to 50 moles %. In the release experiments, the effect of triiodothyronine was also biphasic; the leakage was the highest at 0% and 50% and the lowest at 30 moles % of cholesterol. On the contrary, thyroxine was without effect on liposomes containing cholesterol from 30 to 50 mol %. This fact correlated with a lower incorporation of thyroxine, compared with that of triiodothyronine in liposomes containing up to 30 moles % of cholesterol. The fact that the above differential incorporation of thyroid hormones was also observed at physiological concentration and that most of the mammalian membrane cells have more than 25 moles % of cholesterol have for physiological implications to the observations reported here.
ISSN:0022-2631
1432-1424
DOI:10.1007/BF00233549