title: Adipose tissue extracts plasma ammonia after sprint exercise in women and men.
abstract: This study evaluates a possible contribution of adipose tissue to the elimination of plasma ammonia (NH(3)) after high-intensity sprint exercise. In 14 healthy men and women, repeated blood samples for plasma NH(3) analyses were obtained from brachial artery and from a subcutaneous abdominal vein before and after three repeated 30-s cycle sprints separated by 20 min of recovery. Biopsies from subcutaneous abdominal adipose tissue were obtained and analyzed for glutamine and glutamate content. After exercise, both arterial and abdominal venous plasma NH(3) concentrations were lower in women than in men (P < 0.01 and P < 0.001, respectively). All postexercise measurements showed sex-independent positive arterio-subcutaneous abdominal venous plasma NH(3) concentration differences (a-v(abd)), indicating a net uptake of NH(3) from blood to adipose tissue. However, the fractional extraction (a-v(abd)/a) of NH(3) was higher in women than in men (P < 0.05). The glutamine-to-glutamate ratio in adipose tissue was increased after the second and third bout of sprint exercise (2.2 +/- 0.7 and 1.6 +/- 0.8, respectively) compared with the value at rest (1.2 +/- 0.6), suggesting a reaction of the extracted NH(3) with glutamate resulting in its conversion to glutamine. Adipose tissue may thus play an important physiological role in eliminating plasma NH(3) and thereby reducing the risk of NH(3) intoxication after high-intensity exercise.
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Physiology, Karolinska Institutet, Stockholm, Sweden. mona.esbjornsson@ki.se
authors.forename: Mona
authors.initials: M
authors.lastname: Esbjörnsson
authors.forename: Jens
authors.initials: J
authors.lastname: Bülow
authors.forename: Barbara
authors.initials: B
authors.lastname: Norman
authors.forename: Lene
authors.initials: L
authors.lastname: Simonsen
authors.forename: Jacek
authors.initials: J
authors.lastname: Nowak
authors.forename: Olav
authors.initials: O
authors.lastname: Rooyackers
authors.forename: Lennart
authors.initials: L
authors.lastname: Kaijser
authors.forename: Eva
authors.initials: E
authors.lastname: Jansson
mesh_terms: D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D000641:Ammonia / Q000097:blood*; D001642:Bicycling / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D010807:Physical Endurance / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D012737:Sex Factors
chemical_list: D005973:Glutamine; D018698:Glutamic Acid; D000641:Ammonia