Human and Mouse Brown Adipose Tissue Mitochondria Have Comparable UCP1 Function

• Human BAT has a respiratory capacity 50- to 100-fold greater than that of WAT
• Human BAT has functional UCP1
• Per mitochondrion, UCP1 function is similar in human and rodent BAT
• BAT and skeletal muscle have similar respiratory capacities in humans

SummaryBrown adipose tissue (BAT) plays an important role in mammalian thermoregulation. The component of BAT mitochondria that permits this function is the inner membrane carrier protein uncoupling protein 1 (UCP1). To the best of our knowledge, no studies have directly quantified UCP1 function in human BAT. Further, whether human and rodent BAT have comparable thermogenic function remains unknown. We employed high-resolution respirometry to determine the respiratory capacity, coupling control, and, most importantly, UCP1 function of human supraclavicular BAT and rodent interscapular BAT. Human BAT was sensitive to the purine nucleotide GDP, providing the first direct evidence that human BAT mitochondria have thermogenically functional UCP1. Further, our data demonstrate that human and rodent BAT have similar UCP1 function per mitochondrion. These data indicate that human and rodent BAT are qualitatively similar in terms of UCP1 function.

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