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The Vascular Supply to Human Brown Adipose Tissue
Author(s) -
Coolbaugh Crystal L.,
George Mark K.,
Hooijmans Melissa T.,
Damon Bruce M.
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.06689
Subject(s) - brown adipose tissue , adipose tissue , medicine , magnetic resonance angiography , magnetic resonance imaging , thermogenesis , sagittal plane , venous blood , anatomy , nuclear medicine , radiology
Brown adipose tissue (BAT) engages in non‐shivering thermogenesis in response to cold exposure. Several aspects of its function require significant arterial and venous supplies. For example, the arterial system delivers endocrine signaling molecules and metabolic substrates including glucose and non‐esterified fatty acids to both stimulate and fuel BAT thermogenesis. Heat produced from BAT is then presumed to transfer to the blood passing through the tissue to protect core body temperature in response to the initiating cold stimulus. However, whether human BAT contains such a vascular system is unknown. The purpose of this study was to characterize the arterial and venous supply to supraclavicular BAT. Six healthy subjects [4 men; age: 30.7 ± 5.8 yrs.; body mass index: 21.7 ± 3.5 kg/m 2 ; total body fat % (dual‐energy x‐ray absorptiometry scan): 23.5 ± 6.2 %] underwent time‐of‐flight magnetic resonance angiography (MRA) of the arterial and venous systems and quantitative fat/water MR imaging (FWMRI) to identify BAT. Angiography images were reconstructed at 0.5×0.5×2.0 mm resolution. FWMRI was performed using a 21‐echo spoiled gradient‐echo sequence, with computation of the fat signal fraction using the manufacturer’s algorithms. FWMRI images were reconstructed at 1.0×1.0×4.0 mm resolution and then resized to match the resolution of the MRA data. The supraclavicular BAT depot was hand‐defined from the apex of the lung to its superior margin in the FWMRI images. Coronal, axial, and sagittal maximum intensity projections (MIPs) of the BAT regions were overlaid onto co‐registered MIPs of the arterial and venous angiograms. In five subjects, there was a single, tortuous branch of the second part of the subclavian artery that supplied the BAT depot; in the sixth subject there was insufficient conspicuity to trace this artery back to the subclavian artery. The arterial diameters ranged from 1.5–2.5 mm. In no case was the artery observed to pass completely through the supraclavicular BAT depot. In two subjects, there was a single 3.5 mm diameter vein returning from the head and passing through the medial portion of the BAT. In the other four subjects, there were 3–4 veins with 2–4 mm diameters that returned from the head and that passed through both the medial and lateral portions of the BAT depot. Individuals with the largest diameter arteries also tended to have the most extensive venous systems. These preliminary data suggest that MRA and FWMRI may be used to quantify the arterial and venous supplies of the human supraclavicular BAT depot. The extensive venous supply to BAT, coupled with the absence of arteries passing fully through this BAT depot, together suggest that the primary thermogenic role of the supraclavicular BAT depot is in rewarming blood returning from the head to the central circulation. Support or Funding Information NIDDK/NIH R01‐DK‐105371, NCATS/NIH UL1‐TR000445