In:
American Journal of Physiology-Endocrinology and Metabolism, American Physiological Society, Vol. 277, No. 2 ( 1999-08-01), p. E380-E389
Abstract:
The molecular basis for variations in resting metabolic rate (RMR) within a species is unknown. One possibility is that variations in RMR occur because of variations in uncoupling protein 2 (UCP-2) and uncoupling protein 3 (UCP-3) expression, resulting in mitochondrial proton leak differences. We tested the hypothesis that UCP-2 and -3 mRNAs positively correlate with RMR and proton leak. We treated thyroidectomized and sham-operated mice with triiodothyronine (T 3 ) or vehicle and measured RMR, liver, and skeletal muscle mitochondrial nonphosphorylating respiration and UCP-2 and -3 mRNAs. T 3 stimulated RMR and liver UCP-2 and gastrocnemius UCP-2 and -3 expression. Mitochondrial respiration was not affected by T 3 and did not correlate with UCP-2 and -3 mRNAs. Gastrocnemius UCP-2 and -3 expression did correlate with RMR. We conclude 1) T 3 did not influence intrinsic mitochondrial properties such as membrane structure and composition, and 2) variations in UCP-2 and -3 expression may partly explain variations in RMR. One possible explanation for these data is that T 3 stimulates the leak in vivo but not in vitro because a posttranslational regulator of UCP-2 and -3 is not retained in the mitochondrial fraction.
Type of Medium:
Online Resource
ISSN:
0193-1849
,
1522-1555
DOI:
10.1152/ajpendo.1999.277.2.E380
Language:
English
Publisher:
American Physiological Society
Publication Date:
1999
detail.hit.zdb_id:
1477331-4
SSG:
12
Permalink