Brown adipose tissue (BAT) is an organ specialized to fuel nonshivering thermogenesis for the defense of high body temperature of many eutherian mammals in the cold. Cold-induced sympathetic stimulation of brown adipocytes activates lipolysis, glucose uptake, and mitochondrial biogenesis, with the mitochondrial biogenesis providing a powerful cellular engine for heat generation. At the mitochon...

THE AGING PROCESS RESULTS in an accelerated decline of functional capacity, but the mechanisms behind this decline are unclear (21, 22). The free radical theory of aging proposes that mitochondrial production of reactive oxygen species (ROS) causes an increase in cellular damage with age (9, 10). This theory has gained strong support because it is consistent with many of the processes and degen...

Triiodothyronine regulates energy metabolism and thermogenesis. Among triiodothyronine derivatives, 3,5-diiodo-l-thyronine (T(2)) has been shown to exert marked effects on energy metabolism by acting mainly at the mitochondrial level. Here we investigated the capacity of T(2) to affect both skeletal muscle mitochondrial substrate oxidation and thermogenesis within 1 h after its injection into h...

Triiodothyronine regulates energy metabolism and thermogenesis. Among triiodothyronine derivatives, 3,5-diiodo-L-thyronine (T2) has been shown to exert marked effects on energy metabolism by acting mainly at the mitochondrial level. Here we investigated the capacity of T2 to affect both skeletal muscle mitochondrial substrate oxidation and thermogenesis within 1 hour after its injection into hy...

Weight loss in response to caloric restriction is variable. Because skeletal muscle mitochondrial proton leak may account for a large proportion of resting metabolic rate, we compared proton leak in diet-resistant and diet-responsive overweight women and compared the expression and gene characteristics of uncoupling protein (UCP)2 and UCP3. Of 1,129 overweight women who completed the University...

A significant proportion of standard metabolic rate is devoted to driving mitochondrial proton leak, and this futile cycle may be a site of metabolic control during hibernation. To determine if the proton leak pathway is decreased during metabolic depression related to hibernation, mitochondria were isolated from liver and skeletal muscle of nonhibernating (active) and hibernating arctic ground...

Photodynamic therapy, which consists of treatment with hematoporphyrin derivative (HPD) followed by photoradiation with visible light, is a promising approach to treatment of various cancers. To gain further understanding of the mechanisms whereby this therapy produces cytotoxicity, we undertook a study of the mitochondrial proton-translocating adenosine triphosphatase, an enzyme performing the...

This Application Note describes a method for profiling mitochondrial function in cells responding to stress. The mitochondrial profile generated in this way provides four parameters of mitochondrial function that can be measured in one experiment: basal respiration rate, ATP-linked respiration, proton leak, and reserve capacity. The results described here suggest that the development of cardiom...

Uncoupling proteins (UCPs) belong to a large family of mitochondrial solute carriers 25 (SLC25s) localized at the inner mitochondrial membrane. UCPs transport protons directly from the intermembrane space to the matrix. Of five structural homologues (UCP1 to 5), UCP4 and 5 are principally expressed in the central nervous system (CNS). Neurons derived their energy in the form of ATP that is gene...